applied to the explanation of processes in the sublunary world. in the platonic view, however, the material and formal causes are only subservient or instrumental causes. those causes are in fact immanent in their effects and constitutive elements of the thing they produce. as proclus asserts in prop. 75 of the elements of theology, “ that which exists in the effect is not so much a cause as an auxiliary cause ( sunaition ) or an instrument of the producer. ” causes in the proper sense must act upon their effects from outside, while transcending them. for a proper understanding of what the true causes are of all things, proclus argues, one must follow plato, who lifts us up to the level of the transcendent forms and makes us discover the creative causality of the demiurge and the finality of the good as the ultimate explanation of all aspirations. although aristotle also discusses efficient and final causes, he falls short of a true understanding of creative causality because he abandons the hypothesis of the forms. without the transcendent forms, there can be no explanation of the being of things, only an explanation of their movement and change. given aristotle ' s narrow understanding of nature, it must come as no surprise, proclus notices, that he admits of cases of ‘ spontaneous generation ’ in the sublunary realm, which again restricts the purport of efficient causality. moreover, because of his rejection of the demiurge ( and of the one ), aristotle is also forced to limit efficient causality to the sublunary realm. in fact, in his view there is no cause of existence of the celestial bodies or of the sensible world as a whole : they exist necessarily in all eternity. but, as proclus argues, such a position will force him to admit that the world has the capacity to constitute itself, which is absurd ( see below ). the neoplatonic concept of causality is therefore quite different from that of the peripatetics, even if both share the same terminology, such as final or efficient cause. aristotle ' s causes are primarily intended to explain how things move and change, come to be and cease to be, but also offer to explain what given things are. for the neoplatonists, generalizing a principle formulated in the philebus — “ that everything that comes to be comes to be through a cause ” ( 26e, cf. tim. 28a ) — causality


given things are. for the neoplatonists, generalizing a principle formulated in the philebus — “ that everything that comes to be comes to be through a cause ” ( 26e, cf. tim. 28a ) — causality is of much wider application than the explanation of change and motion, it is not only about what things are, but about what constitutes ( hupostatikos ) their being, and it can be, analogously, used to explain relations between all levels of being. thus we can say of the one that it is the cause of intellect, and of intellect that it is cause of soul. in the timaeus, however, the main interest is to understand what is the cause of the sensible world and all the cosmic beings : this is primarily the demiurge or creator of the world ( the one is not the ‘ creator ’ of intellect ). b. corporeal and incorporeal causes. according to the stoics only bodies and powers or qualities of bodies are capable of acting and being acted upon ( see steel 2002 ). the platonists often criticized the stoic view and pointed to what they thought were the many contradictions involved, in particular, in the materialistic explanation of psychic activities or dispositions such as virtues. they defended the opposite view : all forms of causality must ultimately be explained as emanating from incorporeal entities. proclus adopts plotinus ' view ( iv, 7 8a ), that only incorporeal beings can be causes in the strict sense, and includes it among the basic theorems of his metaphysics. see elem. theol. § 80 ( cf. theol. plat. i 14, p. 61. 23 – 62. 1 ) : every body has by its own nature the capacity to be acted upon, every incorporeal thing the capacity to act, the former being in itself inactive, the latter impassive ; but through association with the body, the incorporeal too is acted upon, just as bodies too can act because of the participation in incorporeal entities. in this proposition proclus first sets apart the corporeal and incorporeal as being active / impassible and passive / inactive respectively. however, the two realms are not absolutely separate from each other. the soul, which is an incorporeal substance, enters into association with the body and thus becomes itself, though only accidentally, subject to different passions


and passive / inactive respectively. however, the two realms are not absolutely separate from each other. the soul, which is an incorporeal substance, enters into association with the body and thus becomes itself, though only accidentally, subject to different passions. the body, on the contrary, may gain great profit from the association with the incorporeal. this is evident in the case of animated bodies, which owe all their vital activities to the presence of the soul in them. but also inanimate natural bodies acquire all capacities and powers from nature and its inherent logoi or organizing rational principles ( see steel 2002 ). c. the relation of cause to its effect. the relation between a cause and its effect is characterized by both similarity and dissimilarity. for every cause produces something that is similar to it, and every effect thus resembles its cause, though in a secondary and less perfect way. but in so far as the effect is really distinguished from its cause, it acquires its own characteristic form of being, which was not yet developed on the level of its cause. for this reason each thing can be said to exist in three manners ( elem. theol. § 65 ). first, it is in itself as expressing formally its own character ( kath ’ hyparxin ). second, it exists in a causal manner ( kat ’ aitian ) being anticipated in its cause. finally, it exists as being participated ( kata methexin ) by the next level of being, which is its effect. thus life is a property of a living organism as being participated by it. life characterizes the soul formally. life also exists qua form in the divine mind. finally, proclus stresses that the higher a cause, the more comprehensive it is, and the further its effects reach ( elem. theol. § 57 ). all things, including matter, which has in itself, apart from the forms existing in it, no ‘ being ’, participate in the one ; all beings participate in being ; all plants and animals participate in life ; all rational souls participate in intellect. proclus ' epistemology is firmly rooted in his theory of the soul. for proclus, souls as self - moving principles represent the lowest level of entities that are capable of reverting upon itself ( so called self - constituted beings [ authypostata ], see elem. theol. § 40 – 51 ). they are incorporeal, separable from bodies and ind


entities that are capable of reverting upon itself ( so called self - constituted beings [ authypostata ], see elem. theol. § 40 – 51 ). they are incorporeal, separable from bodies and indestructible / immortal ( elem. theol. § 186 – 7 ). yet, they are principles of life and of movement of bodies ( elem. theol. § 188 ). in accordance with proclus ' general metaphysical principles ( cf. above 3. 1 ), from the unparticipated soul - monad proceed different kinds of participated soul : divine souls, daemonic souls, human souls, souls of animals ). as with other platonists, proclus frequently discusses the vexed question as to why a soul would descend into a body at all ( ‘ fall of the soul ’ ) ( see dorrie / baltes ( 2002. 2 ) 163 – 218 ). moreover, the neoplatonist distinguishes between altogether three so - called vehicles ( ochemata ) of the soul. the rational soul is permanently housed in the luminous vehicle, while the non - rational soul is located in the pneumatic vehicle. by being incarnated in a human body, soul, or rather, the vegetative soul attains thus a ( third ) ‘ shell - like ’ vehicle. the theory of the different vehicles or the psychic ‘ astral body, ’ familiar nowadays from modern theosophic theories, fulfils several crucial functions in neoplatonic psychology : it explains ( a ) how an incorporeal soul can be linked to a body, ( b ) how souls can move in space, ( c ) how souls can be punished after death ( cf. plato ' s myths ), ( d ) where certain faculties of the soul such as imagination are located. proclus distinguishes between two kinds of vehicles, one mortal and the other immortal ( in tim. iii 236. 31 ff. and elem. theol. § 207 – 210 ). proclus also adheres to the platonic theory of transmigration, but argues that human souls never enter animal bodies as their constitutive forms. for only animal souls can be organizing principles of animal bodies. if some rational souls are ‘ degraded ’ in the next life and forced to live in an animal body because of their misdemeanour in this life, they are only ‘ relationally ’ ( schesei ) present to this


animal bodies. if some rational souls are ‘ degraded ’ in the next life and forced to live in an animal body because of their misdemeanour in this life, they are only ‘ relationally ’ ( schesei ) present to this animal body. proclus distinguishes between the following faculties of soul : sense perception, imagination ( phantasia ), opinion, discursive thought, and intellection. while sense perception and imagination belong to the non - rational soul, opinion forms the lowest level of rationality. the aim of epistemological ascent is to free oneself eventually from the lower psychic faculties, including the lower rational ones, in order to enjoy a state of pure contemplation. as with many other platonists, proclus ' epistemology is based on a theory of innate knowledge ( in accordance with the platonic dictum that ‘ all learning is recollection [ anamnesis ] ’ ). proclus refers to the innate contents of the soul as its reason - principles ( logoi ) or forms ( eide ). these innate reason - principles constitute the essence of soul. that is why they are called ‘ essential reason - principles ’ ( logoi ousiodeis ) ( steel 1997 ). the traditional translation reason - principles was chosen on purpose, because on an ontological level these same logoi serve as principles of all things. they are extended or unfolded images of the forms that exist in intellect ; and by means of them the world - soul with the assistance of nature brings forth everything. in other words, the psychic logoi are instantiations of platonic forms on the level of soul as are the logoi in nature and the forms immanent in matter. according to the fundamental neoplatonic axiom panta en pasin ( ‘ all things are in all things ’ ), forms exist on all levels of reality. but the logoi in soul also offer the principles of all knowledge and are the starting points of demonstration. at in parm. iv 894. 3 – 18 ( ed. steel ) proclus argues that only with reference to these notions within the soul predication is possible ( see helmig 2008 ), since they are universal in the true sense of the word. on the other hand, both transcendent platonic forms and forms in matter are not taken to be universals proper by proclus. the former are rather intelligible particulars, as it were, and cannot be defined ( steel


. on the other hand, both transcendent platonic forms and forms in matter are not taken to be universals proper by proclus. the former are rather intelligible particulars, as it were, and cannot be defined ( steel 2004 ), while the latter are strictly speaking instantiated or individualised universals that are not shared by many particulars ( see helmig 2008, cf. above 3. 1 – 2 ). for this reason, it does not make much sense to talk about ‘ the problem of universals ’ in proclus. it is another crucial assumption of proclus ' epistemology that all souls share the same logoi ( elem. theol. § 194 – 195 ). in terms of concept - formation this entails that psychic concepts, once they are grasped correctly, are universal, objective, and shareable ( see helmig 2011 ). moreover, if all souls share the same logoi, and these logoi are the principles of reality ( see above ), then by grasping the logoi souls come to know the true principles or causes of reality. already aristotle had written that to know something signifies to know its cause ( met. a 3, 983a25 – 26 and an. post. i 2, 71b9 – 12 ). in his commentary on plato ' s timaeus, proclus introduces an interesting distinction. taking his start from the problem of how we can recognise certain objects, he considers the example of an apple. the different senses tell us that there is something sweet, red, even, with a nice smell. and while common sense ( koine aisthesis ) can distinguish the different impressions of the special senses, only opinion ( doxa ) is capable of saying that the object there on the table is an apple. doxa is able to do this, because it has access to the innate logoi of the soul. however, as proclus explains ( in tim. i 248. 11 ff. ), opinion only knows the ‘ that ’ ( hoti ), that is, it can recognize objects. discursive thought ( dianoia ), on the other hand, also knows the ‘ why ’ ( dihoti ), that is, the causes of something. this distinction can also be rephrased in terms of concepts, implying a distinction between factual concepts that allow us to identify or recognise certain objects, and concepts that fulfil an explanatory role. on the whole, procl


something. this distinction can also be rephrased in terms of concepts, implying a distinction between factual concepts that allow us to identify or recognise certain objects, and concepts that fulfil an explanatory role. on the whole, proclus ' reading and systematisation of plato ' s doctrine of learning as recollection makes platonic recollection not only concerned with higher learning, since already on the level of object recognition we employ concepts that originate from the innate logoi of the soul ( helmig 2011 ). proclus argues at length that the human soul has to contain innate knowledge. therefore, one should not consider it an empty writing tablet, as aristotle does ( aristotle, de anima iii 4 ). he is wrong in asserting that the soul contains all things potentially. according to proclus, the soul contains all things ( i. e., all logoi ) in actuality, though due to the ‘ shock of birth ’ it may seem as if the soul has fallen to potentiality. at in crat. § 61, proclus asserts that the soul does not resemble an empty writing tablet ( agraphon grammateion ) and does not possess all things in potentiality, but in act. in eucl. 16. 8 – 13 expresses the same idea : “ the soul is not a writing tablet void of logoi, but it is always written upon and always writing itself and being written on by the intellect. ” as with his philosophy of mathematics, proclus presents a detailed criticism of the view that universal concepts are derived from sensible objects ( by abstraction, induction, or collection ). in the fourth book of his commentary on plato ' s parmenides and in the two prologues of the commentary on euclid we find the most comprehensive criticism of abstractionism in antiquity ( see helmig 2010 and 2011 ). proclus devoted three entire books or ‘ monographs ’ ( monobiblia ) to problems of providence, fate, free choice, and evil. the first treatise ( ten problems concerning providence ) examines ten different problems on providence that were commonly discussed in the platonic school. for proclus providence ( pronoia ) is the beneficent activity of the first principle ( the ‘ source of goods ’ ) and the gods ( henads ), who have their existence before intellect ( pro - nou ). one of the problems discussed is the question of how divine foreknowledge and human free choice can be reconciled. for if god


’ ) and the gods ( henads ), who have their existence before intellect ( pro - nou ). one of the problems discussed is the question of how divine foreknowledge and human free choice can be reconciled. for if god knows not only past and present, but also future events, the outcome of future events is already pre - determined ( as god has a determinate knowledge of all things ), and hence there is no free choice for humans. proclus ' answer, which ultimately goes back to iamblichus, consists in applying the principle that the mode of knowledge is not conditioned by the object known but by the knower. in the case of gods, this entails that they know the contingent event in a non contingent manner, the mutable immutably. they have an undivided knowledge of things divided and a timeless knowledge of things temporal ( elem. theol. § 124, cf. de decem dub. § 6 – 8 ). proclus ' answer was later taken up by ammonius in his commentary on the de interpretatione ix and in boethius ' consolation of philosophy v 6 as well as in his commentary on the de interpretatione ix. the second treatise ( on providence fate and what depends on us ) replies to a letter of theodore, a former friend of proclus. in this letter theodore, an engineer, had defended with several arguments a radical determinism, thus entirely excluding free choice. before refuting theodore ' s arguments, proclus introduces some fundamental distinctions in order to solve the problems raised by his old friend. the first distinction is between providence and fate : providence is essentially a god, whereas fate is something divine, but not a god. this is because it depends upon providence and is as it were an image of it. ( de prov. § 14 ) the second distinction is that between two types of soul : the rational soul is separable from the body, the irrational resides in the body is inseparable from its substrate ; “ the latter depends in its being upon fate, the former upon providence ” ( de prov. § 15 ff. ). the third distinction concerns knowledge and truth : one type of knowledge exists in souls that are bound to the process of generation ; [ … ] another type is present in souls that have escaped from this place. ( de prov. § 3. 1 – 4. 3 ) these three distinctions taken together make it possible for proclus to ultimately reconcile providence, fate


generation ; [ … ] another type is present in souls that have escaped from this place. ( de prov. § 3. 1 – 4. 3 ) these three distinctions taken together make it possible for proclus to ultimately reconcile providence, fate, and free choice. in so far as we are rational agents and let ourselves being determined in our choices only by intelligible principles, we may transcend the determinism of fate to which we belong as corporeal beings. yet, our actions are integrated into the providential order, as we willingly obey the divine principles. the third treatise ( on the existence of evils ) asks why and how evil can exist if the world is governed by divine providence. proclus argues that evil does not have an existence of its own, but only a derivative or parasitic existence ( par - hypostasis, sc. on the good ) ( de mal. § 50 ). in order to exist in a proper sense, an effect must result from a cause which proceeds according to its nature towards a goal that is intended. [ … ] whenever an effect is produced that was not intended or is not related by nature or per se to the agent, it is said to exist besides ( para ) the intended effect, parasitically upon it, as it were. ( opsomer - steel 2003, 25 ) this is precisely the case with evils, which are shortcomings and mistakes. as a failure is never intended qua failure by an agent, but is an unfortunate by - effect of its action, so is evil qua evil never caused by a cause. therefore, proclus continues, it is better to call its mode of existence a parhupostasis, rather than a hupostasis, a term that belongs to those beings “ that proceed from causes towards a goal. ” parhupostasis or “ parasitic existence, ” on the contrary, is the mode of existence of “ beings that neither appear through causes in accordance with nature nor result in a definite end. ” evils are not the outcome of goal - directed processes, but happen per accidens, as incidental by - products which fall outside the intention of the agents. [ … ] therefore it is appropriate to call such generation a parasitic existence ( parhupostasis ), in that it is without end and unintended, uncaused in a way ( anaition pos ) and indefinite. ( de mal. § 50. 3 – 9, 29 – 31


parasitic existence ( parhupostasis ), in that it is without end and unintended, uncaused in a way ( anaition pos ) and indefinite. ( de mal. § 50. 3 – 9, 29 – 31, transl. by opsomer - steel 2003 ) dionysius the areopagite adopted proclus ' views on evil in his work on the divine names. thanks to this adaptation proclus ' doctrine of evil had an enormous influence on the later medieval discussions on evil both in byzantium and in the latin west and dominated the philosophical debates on evil up to the 19th century. a theological physics although proclus composed a short ( presumably early ) treatise where he summarises aristotle ' s theory of movement ( elements of physics ), he does not understand physics primarily as the study of movement and change of natural phenomena, but rather seeks to connect these phenomena to their intelligible and divine causes ( physics as a kind of theology, in tim. i 217. 25 ). in the preface to his commentary on plato ' s timaeus proclus sets out to prove why plato ' s physics, as developed in the timaeus, is superior to natural science in the aristotelian sense ( see steel 2003 ). in proclus ' view plato ' s timaeus not only offers a physiologia, a science of nature in its many aspects, but also presents an explanation of the whole of nature by paying due attention to its incorporeal, divine causes : the natural world proceeds from the demiurge as the expression of an ideal paradigm and aims at the ultimate good. therefore, plato ' s physio - logy is also a sort of theo - logy : the purpose of timaeus will be to consider the universe, insofar as it is produced by the gods. in fact, one may consider the world from different perspectives : insofar as it is corporeal or insofar as it participates in souls, both particular and universal, or insofar as it is endowed with intellect. but timaeus will examine the nature of the universe not only along all those aspects, but in particular insofar as it proceeds from the demiurge. in that respect the physiology seems also to be a sort of theology, since also natural things have somehow a divine existence insofar as they are produced by the gods. ( in tim. i 217. 18 – 27 )


the demiurge. in that respect the physiology seems also to be a sort of theology, since also natural things have somehow a divine existence insofar as they are produced by the gods. ( in tim. i 217. 18 – 27 ) before offering an explanation of the generation of the world, timaeus sets out the fundamental principles that will govern his whole explanation of the physical world ( tim. 27d5 – 28b5 ). as proclus observes, it is the task of a scientist to formulate at the start of his project the principles proper to the science in question, and not just to assume some general axioms. the science of nature too is based on specific axioms and assumptions, which must be clarified before we can move to the demonstration. in order to make phusiologia a real science, the philosopher must deduce his explanation, as does the geometer, from a set of fundamental propositions or axioms. if i may say what i think, it seems to me that plato proceeds here in the manner of the geometers, assuming before the demonstrations the definitions and hypotheses through which he will make his demonstrations, thus laying the foundations of the whole science of nature. ( in tim. i. 217. 18 – 27 ) starting from these fundamental propositions, proclus argues, plato deduces the different types of causality that are required for a truly scientific understanding of nature ( efficient, exemplary, and final cause ; see steel 2003 and above 3. 2 ). time and eternity proclus discusses eternity and time in his commentary on the timaeus and in propositions 53 – 55 of the elements of theology ( see steel 2001 ). aristotle had defined time as a “ measure of movement according to the before and after. ” therefore, anything measured by time must have a form of existence or activity in which a past and a future state can be distinguished. in fact, an entity in time is never wholly and simultaneously what it is, but has an existence extended in a process of before and after. opposed to it stands the eternal, which exists as a simultaneous whole and admits of no composition or change. “ there is no part of it, ” writes proclus, “ which has already subsisted and another that will subsist later, but as yet is not. all that it is capable of being, already possesses it in entirety without losing it or without accumulating ” ( elem. theol. § 52


already subsisted and another that will subsist later, but as yet is not. all that it is capable of being, already possesses it in entirety without losing it or without accumulating ” ( elem. theol. § 52 ). one must distinguish the temporality of things in process from the time by which they are measured. temporal things participate in time, without being time. “ time exists prior to all things in time ” ( elem. theol. § 53 ). with iamblichus, proclus distinguishes absolute time, which is not participated in and exists ‘ prior ’ to all temporal things, from participated time, or rather the many participated times. the same distinctions must also be made regarding eternity. for eternity precedes as cause and measures the multiple eternal beings that participate in it. “ every eternity is a measure of things eternal, every time of things in time ; and these two are the only measures of life and movement in things ” ( elem. theol. § 54 ). to conclude, there are two measures of the duration of things. first there is eternity, which measures at once the whole duration of a being. second, there is time, which measures piecemeal the extension of a being that continually passes from one state to another. eternity can be seen as the prefiguration of time ; time as the image of eternity. each of them governs a separate sphere of reality, eternity the intelligible being, time the temporal ( corporeal and psychic ) world of change. notwithstanding the sharp distinction between the temporal and the eternal realm, there are beings that share in both eternity and time. as proclus notes in the corollary to elem. theol. § 55, “ of the things which exist in time, some have a perpetual duration. ” thus the universe as a whole and the celestial spheres in it are both eternal and temporal. they are eternal because they never come to existence in time and never will cease to exist. but they are temporal because they possess their being only through a process of change in a sequence of moments. the same holds true for the psychic realm : all souls are immortal and indestructible ; nevertheless, they are continually undergoing change. therefore, as proclus says, “ ‘ perpetuity ’ ( aidiotes ) is of two kinds, the one eternal ( aionion ), the other in time ; [ … ] the one having its being concentrated in a simultaneous whole


, as proclus says, “ ‘ perpetuity ’ ( aidiotes ) is of two kinds, the one eternal ( aionion ), the other in time ; [ … ] the one having its being concentrated in a simultaneous whole, the other diffused and unfolded in temporal extension ( paratasis ) ; the one entire in itself, the other composed of parts, each of which exists separately in a sequence of prior and posterior. ” ( elem. theol. § 55, trans. dodds, modified ). the eternity of the world against aristotle ' s critique in de caelo i 10, proclus defends the view that the cosmos is “ both eternal and generated ( genetos ). ” as a corporeal being, the universe cannot produce itself and maintain itself in being. it depends for its existence upon a superior cause, and it is for that reason “ generated. ” this does not prevent it, however, from existing for ever, in an infinite time. as we just saw, proclus distinguishes between what is eternal in an absolute sense ( the intelligible realm ) and what is eternal because it continues to exist for the whole of time, what boethius later called “ aevum ” in distinction from “ aeternum. ” as proclus notices, at the end of the physics ( 8. 10, 266a27 – 28 ), aristotle himself establishes that no body can possess from itself an unlimited power to exist. if the world exists eternally, it must have this power from an incorporeal principle. therefore, aristotle too is forced to admit that the world is somehow generated, though it continues to exist for eternity. for it always receives from its cause its infinite power and never possesses it at once as a whole, because it is limited. the world is eternal, because it has an infinite power of coming to be, not because it exists of infinite power ( in tim. i 252. 11 – 254. 18 ). this disagreement between plato and aristotle is ultimately due to a different view about the first principles of all things. aristotle denies the existence of platonic forms and therefore cannot admit an efficient or creative cause of the universe in the true sense of the word. efficient causality only concerns the sublunary world. the celestial bodies and the world as a whole have no efficient cause of their being, but only a final cause. from this misunderstanding about the first principles follow all the other views that distinguish aristotle from plato. one gets


concerns the sublunary world. the celestial bodies and the world as a whole have no efficient cause of their being, but only a final cause. from this misunderstanding about the first principles follow all the other views that distinguish aristotle from plato. one gets the impression, proclus says, that aristotle, because he could not grasp the first principle of all things - the one – has always to find an explanation of things on a lower level : whatever plato attributes to the one, aristotle attributes to the intellect : that it is without multiplicity, that it is object of desire, that it does not think of secondary things. whatever plato attributes to the demiurgic intellect, aristotle attributes to the heaven and the celestial gods. for, in his view, creation and providence come from them. whatever plato attributes to the substance of heavens [ sc. time ], aristotle attributes to their circular motion. in all these issues he departs from the theological principles and dwells upon the physical explanations beyond what is needed. ( in tim. i 295. 20 – 27 ) the celestial bodies and the place of the universe related to the eternity of the world is the question of the nature of the celestial bodies. aristotle argues in de caelo i 2 that the celestial bodies, which move with a natural circular motion, must be made of a simple substance different from the four sublunary simple bodies ( whose natural movements are in a straight line : up or down ). this ‘ fifth element, ’ which is by nature imperishable, is the ether. with this explanation aristotle seems to oppose the view plato defends in timaeus where it is said that the demiurge made the divine celestial bodies “ mostly out of fire ” ( 40a2 – 4 ). proclus admits that the heaven is composed out of the four elements with a preponderance of fire, but he insists that the elements are not present in the celestial bodies in the same mode as they exist in the sublunary bodies. therefore aristotle is right when he considers the heavens to constitute a fifth nature besides the four elements. “ for in the heavens the elements are not the same as they are here, but are rather the summits of them ” ( in tim. ii 49. 27 – 29 ). if one counts the whole heaven composed out of the best of the elements as one nature and adds to it the four sublunary elements, we may speak of five natures altogether. contrary to aristotle, proclus argues that the whole universe ( to


one counts the whole heaven composed out of the best of the elements as one nature and adds to it the four sublunary elements, we may speak of five natures altogether. contrary to aristotle, proclus argues that the whole universe ( to pan ) is in a place ( topos ). he can do this because his conception of place differs in many respects from aristotle ' s own. the latter defined place as “ the unmoved limit of the surrounding body ” ( physics iv 4, 212a21 – 22 ). from this it follows as a necessary corollary that the universe as a whole cannot be in a place, because there is simply nothing outside it. aristotle ' s definition, as we learn from simplicius ' and philoponus ' corollary on place, had been criticized by all later neoplatonists ( syrianus, proclus, damascius, simplicius, and philoponus ). it is notable that proclus ' own theory of place, as reported by simplicius, differs considerably from other neoplatonic theories in that he considered place an immaterial ‘ body ’, namely a special kind of immobile light. as emerges from proclus ' commentary on plato ' s republic, his theory took inspiration from the column of light mentioned at republic x, 616b. since the heavenly bodies were considered divine, because they are eternal and living beings, the study of the heavens was of special importance to neoplatonists. in the preface to his treatise on astronomical hypotheses ( a summary and evaluation of astronomical views of his time ), proclus makes it clear that his approach is based on plato ' s remarks on astronomy ( especially in the republic and in the laws ). he feels the need to go through the different theories, because one can observe a great disagreement among ancient astronomers on how to explain the different phenomena ( hyp. i § 33 ). fundamental to proclus ' approach is the distinction between two kinds of astronomy ( hyp. i § 1 – 3 ). the first kind contents itself with observing the heavenly phenomena and formulating mathematical hypotheses to explain them and make calculations and prognostics possible. this is the astronomy as practiced by the most famous astronomers before proclus ' time ( aristarchus, hipparchus, and ptolemy ). the second, which is developed by plato in the timaeus, and is confirmed by the tradition of the “


astronomy as practiced by the most famous astronomers before proclus ' time ( aristarchus, hipparchus, and ptolemy ). the second, which is developed by plato in the timaeus, and is confirmed by the tradition of the “ chaldaeans and egyptians, ” investigates into the intelligible causes of heavenly movements. an example for this approach can be found in his commentary on plato ' s republic ( in remp. ii 227. 23 – 235. 3 ). there, proclus explains that the seemingly irregular movements of the planets ought not to be explained by means of ptolemy ' s complicated theory of excentric spheres and epicycles, but are rather due to the fact that the planets are moved by intelligent souls which express in the movements of their bodies “ the invisible powers of the forms ” ( 232. 1 – 4 ). yet proclus appreciates ptolemy ' s astronomy as long as it is seen only as a mathematical - mechanical construction making it possible to calculate and predict the positions of planets, and as long as it does not claim to have any real explanatory value. for the history of astronomy proclus ' astronomical hypotheses remains a most valuable document, since it represents one of the best introductions to ptolemy ' s almagest extant from antiquity and since it explains the most important ancient astronomical theories, in order finally ( in chapter seven of the work ) to evaluate them critically. proclus ' arguments also played an important role in the scientific discussion of the ptolemaic hypotheses in the 16th and 17th century. proclus ' distinctively non - empirical approach towards physics and astronomy also influences his philosophy of mathematics, which is set out in the two prologues to his commentary on the first book of euclid ' s elements. the first prologue deals with the mathematical sciences in general, while the second prologue focuses on geometry proper. proclus argues in great detail that the objects of mathematical sciences cannot be derived from sensible particulars by means of abstraction. because of the imperfect and deficient character of the sensible objects one cannot derive from them objects that are as perfect and as precise as mathematical objects are. therefore, mathematical objects reside primarily in intellect and secondarily in souls ( as logoi ). as universal concepts ( cf. 3. 2 ) we can grasp mathematical objects by means of recollection ( anamnesis ). since geometrical objects are not universal, but particulars, and since by definition they possess extension,


). as universal concepts ( cf. 3. 2 ) we can grasp mathematical objects by means of recollection ( anamnesis ). since geometrical objects are not universal, but particulars, and since by definition they possess extension, proclus argues that their place is human imagination ( phantasia ). imagination acts as a mirror and provides the mathematical objects which are projected into it by the soul with intelligible matter. by means of the latter geometrical objects gain extension and particularity. as with physics and astronomy, the ultimate aim of geometry is not the study of these extended, material objects. rather, geometry serves an anagogical task ( just as in plato ' s republic ), leading the soul upwards to a study of the true and unextended causes of geometrical objects in the divine mind ( in eucl. 54. 14 – 56. 22 ). relying on plato, theaetetus 176a - b late platonists saw the assimilation to god ( homoiosis theoi ) as the goal ( telos ) of philosophy. proclus was faithful to this ideal, as is attested by his biographer marinus ( life of proclus § 25 ). there was a fundamental discussion in late neoplatonism on how this assimilation to the divine was possible for humans. damascius ( in phaed. i § 172 westerink ) distinguishes two tendencies : plotinus and porphyry preferred philosophy, which makes us understand the divine principles of reality through rational explication, while others like iamblichus and his followers, syrianus, and proclus, gave priority to hieratic practice or theurgy ( theourgia, hieratike [ sc. techne ] ). their different evaluation of respectively theory and theurgy as means of salvation may be explained by their different views on the human soul and its possibilities of ascent to the divine realm. while plotinus and porphyry claimed that the superior part of the human soul always remains within the intelligible realm, in touch with the divine principles, and never completely descends into the body, iamblichus, followed by proclus, criticised such a view. the soul does indeed wholly descend into the body ( steel 1976, 34 – 51 ). hence the importance of theurgic rites established by the gods themselves, to make it possible for the human soul to overcome the distance between the mortal and the divine, which cannot be done through increasing philosophical understanding. in


1976, 34 – 51 ). hence the importance of theurgic rites established by the gods themselves, to make it possible for the human soul to overcome the distance between the mortal and the divine, which cannot be done through increasing philosophical understanding. in theol. plat. i 25, proclus expresses his great admiration for the power of theurgy, which surpasses all human knowledge. allegedly, neoplatonic theurgy originated with julian the theurgist, who lived in the time of emperor marcus aurelius. at first sight, theurgy seems to share many characteristics with magic ( theory of cosmic sympathy, invocations, animation of statues of gods and demons ), but it is, as far as we can judge from the extant sources, clearly different from it. in his de mysteriis iamblichus developed a theology of the hieratic rituals from platonic principles, which clearly sets them apart from the vulgar magical practices. while magic assumes that the gods can be rendered subservient to the magicians, platonic philosophers consider this impossible. according to plato ' s principles of theology ( republic ii and laws x ), the gods are immutable, unchangeable, and cannot be bribed by means of sacrifices. proclus ' views on theurgy ( of which only some fragments belonging to his treatise on hieratic art [ i. e., theurgy ] survived ) are fully in line with these fundamental platonic axioms. but how, then, does theurgy work? the theurgists take up an old belief, shared also by many philosophers, namely the natural and cosmic ‘ sympathy ’ ( sumpatheia ) pervading all reality. as with an organism, all parts of reality are somehow linked together as one. another way of expressing this idea is in the neoplatonic principle, going back at least to iamblichus, that everything is in everything ( panta en pasin ). according to proclus, all reality, including its most inferior level, matter, is directed upwards towards the origin from which it proceeds. to say it in the words of theodorus of asine, whom proclus quotes in his commentary on the timaeus ( i 213. 2 – 3 ) : “ all things pray except the first. ” as stated before ( cf. 3. 3 ), the human soul contains the principles ( logoi ) of all reality within itself. the soul


timaeus ( i 213. 2 – 3 ) : “ all things pray except the first. ” as stated before ( cf. 3. 3 ), the human soul contains the principles ( logoi ) of all reality within itself. the soul carries, however, also sumbola or sunthemata which correspond to the divine principles of reality. the same symbols also establish the secret correspondences between sensible things ( stones, plants, and animals ) and celestial and divine realities. thanks to these symbols, things on different levels ( stones, plants, animals, souls ) are linked in a ‘ chain ’ ( seira ) to the divine principle on which they depend, as the chain of the sun and the many solar beings, or the chain of the moon. of great importance in the rituals was also the evocation of the secret divine names. in his commentary on the cratylus, proclus compares divine names to statues of the gods used in theurgy ( in crat. § 46 ), pointing to the fact that also language is an important means in the ascent to the divine. proclus evokes the platonic background of his theurgical beliefs, namely his theory of love ( eros ) as expressed in the symposium and the phaedrus, in his treatise on hieratic art : just as lovers move on from the beauty perceived by the senses until they reach the sole cause of all beautiful and intelligible beings, so too, the theurgists ( hieratikoi ), starting with the sympathy connecting visible things both to one another and to the invisible powers, and having understood that all things are to be found in all things, established the hieratic science. ( trans. ronan, modified ) in the wake of an article of anne sheppard ( 1982 ), scholars usually distinguish between three kinds of theurgy in proclus. the first kind, as described in the above quoted treatise on hieratic art, was mainly concerned with animating statues ( in order to obtain oracles or to evoke divine apparitions ) or, in general, with activities related to physical phenomena or human affairs ( influencing the weather, healing illnesses etc. ) ( see life of proclus § 28 – 29 ). as emerges from our sources, it is this kind of theurgy that involved much ritualistic practice, including hymns and prayers. the second kind of theurgy makes the soul capable of ascending up to the level of the hypercosmic gods and the


emerges from our sources, it is this kind of theurgy that involved much ritualistic practice, including hymns and prayers. the second kind of theurgy makes the soul capable of ascending up to the level of the hypercosmic gods and the divine intellect. this second kind too operates by means of prayers and invocations and it seems especially characteristic of proclus ' hymns. and finally, the third kind of theurgy establishes unity with the first principles, that is the one itself. this third kind corresponds to the level of the highest virtues ( i. e., ‘ theurgic virtues ’ ) in the scale of virtues. it is not clear whether some form of ritual is involved here at all. for this last stage of the platonic homoiosis theoi the following elements are of major importance : negative theology ( culminating in the negation of the negation ), mystic silence and the intriguing notion of faith ( pistis ), which thus enters with a non - platonic meaning - though even for the latter notion proclus will search for confirmation in the platonic dialogues. those who hasten to be conjoined with the good, do no longer need knowledge and activity, but need to be established and a stable state and quietness. what then is it which unites us to the good? what is it which causes in us a cessation of activity and motion? what is it which establishes all divine natures in the first and ineffable unity of goodness? [ … ] it is, in short, the faith ( pistis ) of the gods, which ineffably unites all the classes of gods, of daemons, and of blessed souls to the good. for we should investigate the good not through knowledge ( gnostikos ) and in an imperfect manner, but giving ourselves up to the divine light, and closing the eyes, to become thus established in the unknown and occult unity of beings. for such a kind of faith is more venerable than cognitive activity, not in us only, but with the gods themselves. ( proclus, platonic theology, i 25, trans. th. taylor, modified ). in his lectures on the history of philosophy, in the chapter on alexandrian philosophy, hegel said that “ in proclus we have the culminating point of the neo - platonic philosophy ; this method in philosophy is carried into later times, continuing even through the whole of the middle ages. [ … ] although the neo - platonic


. proclus continued to enjoy wide interest at the turn of the 18th century. thomas taylor ( 1758 – 1835 ) translated all of proclus ' works into english ( reprinted by the prometheus trust [ london ] ) and tried to reconstruct the lost seventh book of the platonic theology. victor cousin ( 1792 – 1867 ) aimed at a complete edition of his preserved work. at the beginning of the 20th century we have the great editions of commentaries in the teubner collection. renewed philosophical interest in proclus in the last century started with the edition of the elements of theology by eric robertson dodds, and carried on with the edition of the platonic theology by henry dominique saffrey, leendert gerrit westerink and, not least, in germany with the works of werner beierwaltes. lists of proclus ' works are available in the two supplements on 1. elements of theology - dodds, e. r., 1933, 19632, the elements of theology, oxford : clarendon. - boese, h., 1987, proclus : elementatio theologica, translata a guillelmo de morbecca, ( series : kul, ancient and medieval philosophy, de wulf - mansion centre, series, 1, vol. 5 ), leuven : leuven university press. 2. platonic theology - saffrey, h. d., and l. g. westerink, 1968 – 1997, proclus : theologie platonicienne, 6 vol., ( series : collection des universites de france ), paris : les belles lettres. - taylor, th, 1816, proclus ' theology of plato, ( series : the thomas taylor series, viii ), london : prometheus trust. 3. - 5. tria opuscula ( latin ) - boese, h., 1960, procli diadochi tria opuscula ( de providentia, libertate, malo ) latine guilelmo de moerbeka vertente et graece ex isaacii sebastocratoris aliorumque scriptis collecta, ( series : quellen und studien zur geschichte der philosophie, 1 ), berlin : de gruyter. 3. ten problems concerning providence - isaac, d., 1977, proclus : trois etudes sur la providence, i. dix problemes concernant la


geschichte der philosophie, 1 ), berlin : de gruyter. 3. ten problems concerning providence - isaac, d., 1977, proclus : trois etudes sur la providence, i. dix problemes concernant la providence, ( series : collection des universites de france ), paris : les belles lettres. - opsomer, j. and steel, c., forthcoming, proclus : ten doubts concerning providence, ( series : the greek commentators on aristotle ), london : duckworth. 4. on providence, fate and what depends on us - isaac, d., 1979, proclus : trois etudes sur la providence, ii. providence, fatalite, liberte, ( series : collection des universites de france ), paris : les belles lettres. - steel, c., 2007, proclus : on providence, ( series : the greek commentators on aristotle ), london : duckworth. 5. on the existence of evils - isaac, d., 1982, proclus : trois etudes sur la providence, iii. de l ' existence du mal, ( series : collection des universites de france ), paris : les belles lettres. - opsomer, j., and c. steel, 2003, proclus : on the existence of evils, ( series : the greek commentators on aristotle, 50 ), london : duckworth. 6. commentary on plato ' s alcibiades ( up to 116b ) - segonds, a. - ph., 1985 - 1986, proclus : sur le premier alcibiade de platon, 2 vol., ( series : collection des universites de france ), paris : les belles lettres. - o ' neill, w., 1964, 19712, proclus : alcibiades i, the hague : martinus nijhoff. 7. commentary on plato ' s cratylus ( up to 407c ) - pasquali, g., 1908, proclus diadochus in platonis cratylum commentaria, ( series : bibliotheca scriptorum graecorum et romanorum teubneriana ), leipzig : teubner [ reprint stuttgart : teubner, 1994 ]. - duvick, b., 2007, proclus. on plato ' s cratylus, ( series : the ancient commentators on aristotle ), london


, leipzig : teubner [ reprint stuttgart : teubner, 1994 ]. - duvick, b., 2007, proclus. on plato ' s cratylus, ( series : the ancient commentators on aristotle ), london : duckworth. 8. commentary on plato ' s timaeus ( up to 44d ) - diehl, e., 1903 – 1906, procli diadochi in platonis timaeum commentaria, ( series : bibliotheca scriptorum graecorum et romanorum teubneriana ), leipzig : teubner [ reprint amsterdam : hakkert, 1965 ]. - tarrant, h., 2007, proclus. commentary on plato ' s timaeus. vol 1, book i : proclus on the socratic state and atlantis, cambridge : cambridge university press. - baltzly, d., 2007, proclus. commentary on plato ' s timaeus. vol 3, book iii : proclus on the world ' s body, cambridge : cambridge university press. ( see the review by c. steel, exemplaria classica 14 ( 2010 ), 425 – 433 ). - runia, d. t., and m. share, 2008, proclus. commentary on plato ' s timaeus. vol 2, book ii : proclus on the causes of the cosmos and its creation, cambridge : cambridge university press. - festugiere, a. - j., 1966 - 1968, commentaire sur le timee, 5 vol., ( series : bibliotheque des textes philosophiques ), paris : vrin. 9. commentary on plato ' s parmenides ( up to 142a ) - steel, c., 2007 – 2009, procli in platonis parmenidem commentaria ( edition prepared with the collaboration of p. d ' hoine, a. gribbomont, c. mace and l. van campe ) ( series : oxford classical texts ), 3 volumes, oxford : clarendon. - segonds, a. - ph., and c. luna, 2007, proclus. commentaire sur le parmenide de platon. tome 1, 1re partie : introduction generale, 2e partie : livre i, texte, ( series : collection des universites de france ), paris : les belles let


sur le parmenide de platon. tome 1, 1re partie : introduction generale, 2e partie : livre i, texte, ( series : collection des universites de france ), paris : les belles lettres ( on this edition see c. steel, mnemosyne 63 ( 2010 ), 120 – 142 ). - morrow, g. r., and j. m. dillon, 1987, proclus ' commentary on plato ' s parmenides, princeton ( new jersey ) : princeton university press. 10. commentary on plato ' s republic ( in different essays ) - kroll, w., 1899 – 1901, procli diadochi in platonis rem publicam commentarii, 2 vol., ( series : bibliotheca scriptorum graecorum et romanorum teubneriana ), leipzig : teubner [ reprint amsterdam : hakkert, 1965 ]. - festugiere, a. - j., 1970, proclus : commentaire sur la republique, 3 vol., ( series : bibliotheque des textes philosophiques ), paris : vrin. 11. elements of physics - ritzenfeld, a., 1912, procli diadochi lycii institutio physica, ( series : bibliotheca scriptorum graecorum et romanorum teubneriana ), leipzig : teubner. - boese, h., 1958, die mittelalterliche ubersetzung der stoicheiosis phusike des proclus, ( series : deutsche akademie der wissenschaften zu berlin, institut fur griechisch - romische altertumskunde, veroffentlichungen 6 ), berlin : akademie verlag. 12. commentary on euclid ' s elements, book i - friedlein, g., 1967, procli diadochi in primum euclidis elementorum librum commentarii, ( series : bibliotheca scriptorum graecorum et romanorum teubneriana ), leipzig : teubner [ reprint hildesheim : olms, 1967 ]. - morrow, g. r., 1970, a commentary on the first book of euclid ' s elements, princeton ( n. j. ) : princeton university press [ reprinted 1992


reprint hildesheim : olms, 1967 ]. - morrow, g. r., 1970, a commentary on the first book of euclid ' s elements, princeton ( n. j. ) : princeton university press [ reprinted 1992, with a new foreword by i. mueller ]. - new edition prepared by c. steel, g. van riel and l. van campe, first volume forthcoming, paris, vrin. 13. exposition of astronomical hypotheses - manitius, c., 1909, procli diadochi hypotyposis astronomicarum positionum, ( series : bibliotheca scriptorum graecorum et romanorum teubneriana ), leipzig : teubner ; reprint stuttgart : teubner 1974. 14. ( frag. ) on the eternity of the world, against the christians ( 18 arguments ) - rabe, h, 1899, ioannes philoponus : de aeternitate mundi contra proclum, leipzig : teubner [ reprint hildesheim : olms, 1963 ]. - lang, h. s., macro, a. d., and j. mcginnis, 2001, proclus : on the eternity of the world ( de aeternitate mundi ), berkeley / los angeles / london : university of california press. - gleede, b., 2009, platon und aristoteles in der kosmologie des proklos. ein kommentar zu den 18 argumenten fur die ewigkeit der welt bei johannes philoponos ( series : studien und texte zu antike und christentum ) tubingen : mohr. 15. ( frag. ) commentary on hesiod, works and days - marzillo, p., 2010, der kommentar des proklos zu hesiods ‘ werken und tagen ’. edition, ubersetzung und erklauterung der fragmente, tubingen : narr. - vogt, e., 1957, procli hymni accedunt hymnorum fragmenta ; epigrammata, scholia, fontium et locorum similium apparatus, indices, wiesbaden : harrassowitz. - van den berg, r. m., 2001, proclus ' hymns : essays, translations, commentary, leiden – boston – koln : brill.


1961, la filosofia dei greci nel suo sviluppo storico, parte iii : la filosofia post - aristotelica, vol. vi : giamblico e la scuola di atene, firenze : la nuova italia, pp. 118 – 196. - bastid, p., 1969, proclus et le crepuscule de la pensee grecque, ( series : bibliotheque d ' histoire de la philosophie ), paris : vrin. - le neoplatonisme, 1971, actes du colloque international organise a royaumont 9 – 13 juin 1969, ( series : colloques internationaux du cnrs ), paris : editions du cnrs. - trouillard, j., 1972, l ' un et l ' ame selon proclos, ( series : collection d ' etudes anciennes ), paris : les belles lettres. - de jamblique a proclus, 1975, neuf exposes suivis de discussions, ( series : entretiens sur l ' antiquite classique, 21 ), vandoeuvres - geneve : fondation hardt. - beierwaltes, w., 1965, 1979², proklos. grundzuge seiner metaphysik, frankfurt am main : vittorio klostermann. - pepin, j., and h. d. saffrey ( eds. ), 1987, proclus lecteur et interprete des anciens, actes du colloque international du cnrs, paris 2 – 4 oct. 1985, ( series : colloques internationaux du cnrs ), paris : editions du cnrs. - boss, g., and g. seel ( eds. ), 1987, proclus et son influence, actes du colloque de neuchatel, juin 1985, zurich : editions du grand midi. - duffy, j., and j. peradotto ( eds. ), 1988, gonimos. neoplatonic and byzantine studies presented to leendert g. westerink at 75., buffalo ( new york ) : arethusa. - reale, g., introduzione a proclo, ( series : i filosofi,


byzantine studies presented to leendert g. westerink at 75., buffalo ( new york ) : arethusa. - reale, g., introduzione a proclo, ( series : i filosofi, 51 ), roma - bari : laterza. - bos, e. p., and p. a. meijer ( eds. ), 1992, on proclus and his influence in medieval philosophy, ( series : philosophia antiqua, 53 ), leiden - koln - new york : brill. - siorvanes, l., 1996, proclus. neo - platonic philosophy and science, new haven : yale university press. - cleary, j. ( ed. ), 1997, the perennial tradition of neoplatonism, ( series : ancient and medieval philosophy, series i, 24 ), leuven : leuven university press. - segonds, a. ph., and c. steel ( eds. ), 2000, proclus et la theologie platonicienne, actes du colloque international de louvain ( 13 – 16 mai 1998 ) en l ' honneur de h. d. saffrey et l. g. westerink, ( series : ancient and medieval philosophy, series i, 26 ), leuven - paris : leuven university press / les belles lettres. - perkams, m., and r. m. piccione ( eds. ), 2006, proklos. methode, seelenlehre, metaphysik, akten der konferenz in jena am 18. - 20. september 2003, ( series : philosophia antiqua, 98 ), leiden - boston : brill. - steel, c., 2006, “ neoplatonism ” and “ proclus, ” in encyclopedia of philosophy, d. m. borchert ( ed. ), detroit : macmillan reference usa, vol. 6, col. 546 – 557 ; vol. 8, col. 40 – 44. - beierwaltes, w., 2007, procliana. spatantikes denken und seine spuren, frankfurt am main : v. klostermann. - steel, c., 2011, “ proclus, ” in the cambridge history of philosophy in late antiquity, l. gerson ( ed. ), cambridge : cambridge university


. sentences, l. brisson ( ed. ), 2 vol., paris : vrin, i, pp. 139 – 274. - – – –, 2007, “ the libraries of the neoplatonists. an introduction, ” in the libraries of the neoplatonists, proceedings of the meeting of the european science foundation ‘ late antiquity and arabic thought : patterns in the constitution of european thought ’ held in strasbourg, march 12 – 14, 2004, c. d ' ancona ( ed. ), ( series : philosophia antiqua, 107 ), leiden - boston : brill, pp. xiii – xxxvi. - d ' ancona, c., and r. c. taylor, 2003, “ liber de causis, ” in dictionnaire des philosophes antiques., r. goulet, j. - m. flamand, and m. aouad, paris : cnrs, pp. 599 – 647. - d ' hoine, p., 2004, “ four problems concerning the theory of ideas : proclus, syrianus and the ancient commentaries on the parmenides, ” in platonic ideas and concept formation in ancient and medieval thought, g. van riel, and c. mace ( eds. ), ( series : ancient and medieval philosophy, series i, 32 ), leuven : leuven university press, pp. 9 – 29. - – – –, 2006, “ the status of the arts. proclus ' theory of artefacts, ” elenchos, 27 : 305 – 344. - de haas, f. a. j., 1997, john philoponus ' new definition of prime matter : aspects of its background in neoplatonism & the ancient commentary tradition, ( series : philosophia antiqua, 69 ), leiden - boston - koln : brill. - di pasquale barbanti, m., 1983, 19932, proclo tra filosofia e teurgia, catania : bonanno. - dillon, j. m., 1972, “ iamblichus and the origin of the doctrine of henads, ” phronesis, 17 : 102 – 106. - – – –, 1986, “ proclus and the forty logoi of zeno, ” illinois classical studies, 11 : 35 – 41. - dillon, j. m., and s.


( pp. 535 – 550 ) ]. - gersh, s., 1973, κινησις ακινητος. a study of spiritual motion in the philosophy of proclus, leiden : brill. - – – –, 1978, from iamblichos to eriugena. an investigation of the prehistory and evolution of the pseudo - dionysian tradition, ( series : studien zur problemgeschichte der antiken und mittelalterlichen philosophie, 8 ), leiden : brill. - gerson, l. p., 1997, “ epistrophe eis heauton : history and meaning, ” documenti e studi sulla tradizione filosofica medievale, 8 : 1 – 32. - – – –, 2005, aristotle and other platonists, ithaca – london : cornell university press. - gritti, e., 2008, proclo. dialettica, anima, esegesi, ( series : il filarete, collana die studi e testi ), milano : led. - gunther, h. - chr., 2007, die uebersetzung der elementatio theologica des proklos und ihre bedeutung fur den proklostext, leiden : brill. - hankins, j., and w. bowen ( eds. ), 2001 – 2006, marsilio ficino. platonic theology, 6 vol., ( series : i tatti renaissance library ), cambridge ( mass. ) : harvard university press. - hankinson, r. j., 1998, cause and explanation in ancient greek thought, oxford : clarendon. - halfwassen, j., 1999, hegel und der spatantike neuplatonismus. untersuchungen zur metaphysik des einen und des nous in hegels spekulativer und geschichtlicher deutung, ( series : hegel studien, 40 ), bonn : bouvier. - harari, o., 2006, “ methexis and geometrical reasoning in proclus ' commentary on euclid ' s elements, ” oxford studies in ancient philosophy, 30 : 361 – 389. - helmig, c., 2004, “ what is the systematic place of abstraction and concept formation in plato


proclus ' commentary on euclid ' s elements, ” oxford studies in ancient philosophy, 30 : 361 – 389. - helmig, c., 2004, “ what is the systematic place of abstraction and concept formation in plato ' s philosophy? ancient and modern readings of phaedrus 249b - c, ” in platonic ideas and concept formation in ancient and medieval thought, g. van riel, and c. mace ( eds. ), ( series : ancient and medieval philosophy, series i, 32 ), leuven : leuven university press, pp. 83 – 97. - – – –, 2008, “ proclus and other neoplatonists on universals and predication, ” documenti e studi sulla tradizione filosofica medievale, 19 : 31 – 52. - – – –, 2009, “ ‘ the truth can never be refuted ’ – syrianus ' view ( s ) on aristotle reconsidered, ” in syrianus et la metaphysique de l ' antiquite tardive, a. longo ( ed. ), ( series : elenchos, 51 ), rome : bibliopolis, 347 – 380. - – – –, 2010, “ proclus ' criticism of aristotle ' s theory of abstraction and concept formation in analytica posteriora ii 19 and elsewhere, ” in interpreting aristotle ' s posterior analytics in late antiquity and beyond, f. a. j. de haas, and m. e. m. p. j. leunissen, and m. martijn ( eds. ), ( series : philosophia antiqua, 124 ), leiden – boston – koln : brill, 27 – 54. - – – –, 2011, forms and concepts — concept formation in the platonic tradition. a study on proclus and his predecessors, ( series : philosophia antiqua ), leiden – boston – koln : brill [ forthcoming ]. - klibansky, r., 1981, the continuity of the platonic tradition during the middle ages, with a new preface and four supplementary chapters together with plato ' s parmenides in the middle ages and the renaissance, with a new introductory preface, munchen : kraus. - kremer, k., 1966, 19712, die neuplatonische seinsphilosophie und ihre wirkung auf thomas von aquin


renaissance, with a new introductory preface, munchen : kraus. - kremer, k., 1966, 19712, die neuplatonische seinsphilosophie und ihre wirkung auf thomas von aquin, ( series : studien zur problemgeschichte der antiken und mittelalterlichen philosophie, 1 ), leiden : brill. - kuisma, o., 1996, proclus ' defense of homer, ( series : commentationes humanarum litterarum, 109 ), helsinki : societas scientiarum fennica. - kutash, e., 2011, ten gifts of the demiurge : proclus on plato ' s timaeus, london / new york : bristol classical press. - lang, h. s., 2005, “ perpetuity, eternity, and time in proclus ' cosmos, ” phronesis, 50 : 150 – 169. - lernould, a., 1987, “ la dialectique comme sciene premiere chez proclus, ” revue des sciences philosophiques et theologiques, 71 : 509 – 535. - – – –, 2001, physique et theologie : lecture du timee de platon par proclus, villeneuve d ' ascq ( nord ) : presses universitaires du septentrion. - linguiti, a., 1990, l ' ultimo platonismo greco : principi e conoscenza, ( series : accademia toscana di scienze e lettere la colombaria. studi, 112 ), firenze : olschki. - lloyd, a. c., 1990, the anatomy of neoplatonism, oxford : clarendon. - mansfeld, j., 1994, prolegomena : questions to be settled before the study of an author, or a text, ( series : philosophia antiqua, 61 ), leiden : brill. - martijn, m., 2010, proclus on nature. philosophy of nature and its methods in proclus ' commentary on plato ' s timaeus, ( series : philosophia antiqua, 121 ), leiden : brill. - o ' meara, d. j., 1986, “ le probleme de la metaphysique


commentary on plato ' s timaeus, ( series : philosophia antiqua, 121 ), leiden : brill. - o ' meara, d. j., 1986, “ le probleme de la metaphysique dans l ' antiquite tardive, ” freiburger zeitschrift philosophie und theologie, 33 : 3 – 22. - – – –, 1989, pythagoras revived. mathematics and philosophy in late antiquity, oxford : clarendon. - opsomer, j., 2000, “ proclus on demiurgy and procession. a neoplatonic reading of the timaeus, ” in reason and necessity. essays on plato ' s ‘ timaeus ’, m. r. wright ( ed. ), london : duckworth, pp. 113 – 143. - – – –, 2001, “ proclus vs plotinus on matter ( de mal. subs. 30 – 7 ), ” phronesis, 46 : 154 – 188. - – – –, 2003, “ la demiurgie des jeunes dieux selon proclus, ” les etudes classiques, 71 : 5 – 49. - – – –, 2006, “ to find the maker and father. proclus ' exegesis of plato tim. 28c3 – 5, ” etudes platoniciennes, 2 : 261 – 283. - opsomer, j., and c. steel, 1999, “ evil without a cause : proclus ' doctrine on the origin of evil, and its antecedents in hellenistic philosophy, ” in zur rezeption der hellenistischen philosophie in der spatantike, akten der 1. tagung der karl - und - gertrud - abel - stiftung vom 22. - 25. september 1997 in trier, th. fuhrer, and m. erler ( eds. ), ( series : philosophie der antike, 9 ), stuttgart : steiner, pp. 229 – 260. - phillips, j., 2007, order from disorder. proclus ' doctrine of evil and its roots in ancient platonism, ( series : ancient mediterranean and medieval texts and contexts ; studies in platonism, neoplatonism, and the platonic tradition, 5 ), leiden : brill. - pichler, r., 2006, allegorese und ethik bei pro


mediterranean and medieval texts and contexts ; studies in platonism, neoplatonism, and the platonic tradition, 5 ), leiden : brill. - pichler, r., 2006, allegorese und ethik bei proklos. untersuchungen zum kommentar zu platons politeia, ( klassische philologie, 2 ), berlin : frank & timme. - podskalsky, g., 1976, “ nikolaos von methone und die proklosrenaissance in byzanz ( 11. - 12. jh. ), ” orientalia christiana periodica, 42 : 509 – 523. - praechter, k., 1973, kleine schriften, h. dorrie ( ed. ), hildesheim : olms. - radke, g., 2006, das lacheln des parmenides, proklos ' interpretationen zur platonischen dialogform, ( series : untersuchungen zur antiken literatur und geschichte, 78 ), berlin - new york : de gruyter. - roth, v. m., 2008, das ewige nun. ein paradoxon in der philosophie des proklos, ( series : philosophische schriften, 72 ), berlin : dunckler & humblot. - saffrey, h. d., 1987, recherches sur la tradition platonicienne au moyen age et a la renaissance, paris : vrin. - – – –, 1990, recherches sur le neoplatonisme apres plotin, ( series : histoire des doctrines de l ' antiquite classique, 14 ), paris : vrin. - – – –, 2000, le neoplatonisme apres plotin, ( series : histoire des doctrines de l ' antiquite classique, 24 ), paris : vrin. - – – –, 2002, l ' heritage des anciens au moyen age et a la renaissance, ( series : histoire des doctrines de l ' antiquite classique, 28 ), paris : vrin. - sezgin, f., 2000, proclus arabus and the liber de causis ( buruklus ‘ inda l - ‘ arab wa - kitab al - idah fi l - khayr


. - sezgin, f., 2000, proclus arabus and the liber de causis ( buruklus ‘ inda l - ‘ arab wa - kitab al - idah fi l - khayr al - mahd ), frankfurt am main : institute for the history of arabic - islamic science at the johann wolfgang goethe university. - sheppard, a. d. r., 1980, studies on the 5th and 6th essays of proclus ' commentary on the republic, gottingen : vandenhoeck & ruprecht. - – – –, 1 982, “ proclus ' attitude to theurgy, ” corolla londiniensis, 32 : 212 – 224. - steel, c., 1978, the changing self. a study on the soul in later neoplatonism : iamblichus, damascius and priscianus, brussel : paleis der academien. - – – –, 1991, “ the one and the good : some reflections on a neoplatonic identification, ” in the neoplatonic tradition. jewish, christian and islamic themes, a. vanderjagt, and d. patzold ( eds. ), ( series : dialectica minora, 3 ), koln : dinter, pp. 9 – 25. - – – –, 1997, “ breathing thought. proclus on the innate knowledge of the soul, ” in the perennial tradition of neoplatonism, j. cleary ( ed. ), ( series : ancient and medieval philosophy, series 1, 24 ), leuven : leuven university press, pp. 293 – 309. - – – –, 1999, “ proclus on the existence of evil, ” and s. menn, “ commentary on steel, ” in proceedings of the boston area colloquium in ancient philosophy, vol. 14, j. j. cleary ( ed. ), leiden – new york – koln : brill, pp. 83 – 109. - – – –, 2001, “ the neoplatonic doctrine of eternity and time and its influence on medieval philosophy, ” in : the medieval concept of time. studies on the scholastic debate and its reception in early modern philosophy, p. porro ( ed. ), ( series : studien und texte zur geistesgeschichte des mittelalters, 75 ) leiden – new york – koln : brill


and its reception in early modern philosophy, p. porro ( ed. ), ( series : studien und texte zur geistesgeschichte des mittelalters, 75 ) leiden – new york – koln : brill, pp. 3 – 31. - – – –, 2002, “ neoplatonic versus stoic causality : the case of the sustaining cause ( ‘ sunektikon ’ ), ” in quaestio 2 : causality, c. esposito, and p. porro ( eds. ), ( series : yearbook of the history of metaphysics ), turnhout : brepols, pp. 77 – 93. - – – –, 2003, “ why should we prefer plato ' s timaeus to aristotle ' s physics? proclus ' critique of aristotle ' s causal explanation of the physical world, ” in ancient approaches to plato ' s timaeus, r. w. sharples, and a. sheppard ( eds. ), ( series : bulletin of the institute of classical studies. supplement, 78 ), london : institute of classical studies, pp. 175 – 187. - – – –, 2004, “ definitions and ideas, ” in proceedings of the boston area colloquium in ancient philosophy, vol. 19, j. j. cleary, and g. m. gurtler ( eds. ), leiden : brill, 103 – 121. - – – –, 2005a, “ theology as first philosophy. the neoplatonic concept of metaphysics, ” in quaestio 5. metaphysica, sapientia, scientia divina. soggetto e statuto della filosofia prima nel medioevo, atti del convegno della societa italiana per lo studio del pensiero medievale, bari, 9 – 12 giugno 2004, p. porro ( ed. ), brepols : turnhout, 3 – 21. - – – –, 2005b, “ proclus ' defence of the timaeus against aristotle ' s objections. a reconstruction of a lost polemical treatise, ” in plato ' s timaeus and the foundations of cosmology in late antiquity, the middle ages and renaissance, th. leinkauf, and c. steel ( eds. ), ( series : ancient and medieval philosophy, i 34 ), leuven : leuven university


and the foundations of cosmology in late antiquity, the middle ages and renaissance, th. leinkauf, and c. steel ( eds. ), ( series : ancient and medieval philosophy, i 34 ), leuven : leuven university press, pp. 163 – 193. - – – –, 2008, “ proclus on the mirror as metaphor of participation, ” in miroir et savoir. la transmission d ' un theme platonicien, des alexandrins a la philosophie arabo - musulmane, d. de smet, m. sebti, and g. de callatay ( eds. ), leuven : leuven university press, pp. 79 – 96. - – – –, 2010, “ proclus, ” in the cambridge history of late ancient philosophy, l. p. gerson ( ed. ), cambridge : cambridge university press [ forthcoming ]. - tarrant, h., and baltzly, d. ( eds. ), 2006, reading plato in antiquity, london : duckworth. - trouillard, j., 1982, la mystagogie de proclos, paris : les belles lettres. - van den berg, r. m., 2008, proclus ' commentary on the cratylus in context. ancient theories of language and naming, ( series : philosophia antiqua, 112 ), leiden – boston : brill. - van liefferinge, c., 1999, la theurgie : des ‘ oracles chaldaiques ’ a proclus, ( series : kernos. supplement, 9 ), liege : centre international d ' etude de la religion greque antique. - van riel, g., 2000, pleasure and the good life. plato, aristotle and the neoplatonists, ( series : philosophia antiqua, 85 ), leiden – new york – koln : brill. - watts, e. j., 2006, city and school in late antique athens and alexandria, ( series : the transformation of the classical heritage, 41 ), berkeley : university of california press. - westerink, l. g., j. trouillard, and a. p. segonds, 1990, prolegomenes a la philosophie de platon, ( series : collection des universites de france ), paris : les belles lettres


j. trouillard, and a. p. segonds, 1990, prolegomenes a la philosophie de platon, ( series : collection des universites de france ), paris : les belles lettres. - whittaker, j., 1975, “ the historical background of proclus ' doctrine of the authypostata, ” in de jamblique a proclus, h. dorrie, ( series : fondation hardt. entretiens tome, 21 ), geneve : vandœuvres, pp. 193 – 230 [ reprint in : studies in platonism and patristic thought, ( series : variorum reprints ), london : aldershot, 1984, xvi. how to cite this entry. preview the pdf version of this entry at the friends of the sep society. look up this entry topic at the indiana philosophy ontology project ( inpho ). enhanced bibliography for this entry at philpapers, with links to its database. - bibliography proclus – dwmc, university of leuven. - editions and translations proclus – dwmc, university of leuven. - repertoire des sources philosophiques antiques ( cnrs – paris ). - search on proclus at the open library. - w. j. hankey, french neoplatonism in the 20th century, in animus 4 ( 1999 ). the authors would like to thank radek chlup ( prague ), antonio luis costa vargas ( berlin ), and sabrina lange ( berlin ) for comments.


june 22, 1976. north atlantic. at 21 : 13 gmt a pale orange glow behind a bank of towering cumulus to the west was observed. two minutes later a white disc was observed while the glow from behind the cloud persisted. high probability that this may have been caused by interferometry using 3 - dimensional artificial scalar wave? fourier expansions? as the interferers. marine observer. 47 ( 256 ), apr. 1977. p. 66 - 68. " unidentified phenomenon, off barbados, west indies. " august 22, 1969. west indies. luminous area bearing 310 degrees grew in size and rose in altitude, then turned into an arch or crescent. high probability that this may have been caused by interferometry using artificial scalar wave? ( ( fourier expansions. ) ) marine observer. 40 ( 229 ), july, 1970. p. 107 - 108. " optical phenomenon : caribbean sea ; western north atlantic. " mar. 20, 1969. caribbean sea and western north atlantic. at 23 : 15 gmt, a semicircle of bright, milky - white light became visible in the western sky and rapidly expanded upward and outward during the next 10 minutes, dimming as it expanded. high probability that this may be caused by interferometry using artificial scalar wave? fourier expansions?. marine observer, 40 ( 227 ), jan. 1970. p. 17 ; p. 17 - 18. 7b. 21 - electricity 13. 06 - triple currents of electricity 14. 35 - teslas 3 6 and 9 ( ( 16. 04 - nikola nikola tesla describing what electricity is ) ) 16. 07 - electricity is a polar exchange 16. 10 - positive electricity 16. 16 - negative electricity - russell 16. 17 - negative electricity - tesla 16. 29 - triple currents of electricity ( ( figure 16. 04. 05 and figure 16. 04. 06 - nikola nikola tesla and lord kelvin ) ) part 16 - electricity and magnetism tesla - electricity from space what electricity is - bloomfield moore page last modified on wednesday 19 of may, 2010 05 : 23 : 05 mdt


credit : ingram publishing / thinkstock “ sanitation : a global estimate of sewerage connections without treatment and the resulting impact on mdg progress ” environmental science & technology it may be the 21st century, with all its technological marvels, but 6 out of every 10 people on earth still do not have access to flush toilets or other adequate sanitation that protects the user and the surrounding community from harmful health effects, a new study has found. the research, published in acs ’ journal environmental science & technology, says the number of people without access to improved sanitation is almost double the previous estimate. jamie bartram and colleagues explain that the current definition of “ improved sanitation ” focuses on separating humans from human excrement, but does not include treating that sewage or other measures to prevent it from contaminating rivers, lakes and oceans. using that definition, 2010 united nations estimates concluded that 4. 3 billion people had access to improved sanitation and 2. 6 billion did not. the new estimates used what the authors regarded as a more realistic definition from the standpoint of global health, since untreated sewage is a major cause of disease. they refined the definition of “ improved sanitation ” by discounting sewage systems lacking access to sewage treatment. they concluded that about 60 percent of the world ’ s population does not have access to improved sanitation, up from the previous estimate of 38 percent.


this file is also available in adobe acrobat pdf format agriculture has always been absolutely necessary for the very survival of humankind. for centuries, it has provided people with food, clothing, and heating, and it has employed most of the total active population. nowadays, we dress mainly in artificial and synthetic fibers and heat themselves with fossil fuels, but the primary sector still supplies all the food we need. the available projections suggest that the world population will grow further in the next decades, while the nutritional status of the world poor must improve. thus, agricultural production has to rise, and it has to rise with little or no further environmental damage : modern agriculture has, in fact, the reputation, largely deserved, of being environment - unfriendly. the challenges ahead, however, should not let people forget the past achievements. 1 from 1800 to 2000, the world population has risen about six - to sevenfold, from less than one billion to six billion. 2 yet, world agricultural production has increased substantially faster - - at the very least, tenfold in the same period. nowadays, people are better fed than in the past : each person in the world has, in theory, 2, 800 calories available, with a minimum of some 2, 200 in sub - saharan africa. 3 famines, which haunted preindustrial times, have disappeared from most of the world. the latest survey by the food and agricultural organization ( fao ) estimates that 800 million people ( i. e., some 10 - 15 % of the world population ) are still undernourished - - but this may be an overestimation, and the proportion has drastically fallen by about a quarter since 1970. 4 furthermore, undernourishment and famine are caused much more by the skewed distribution of income ( poor entitlements in sen ' s definition ) and by political events ( international wars, civil wars, terrorism ), than by sheer lack of food. 5 actually, many oecd countries have, since the 1950s, been struggling with an overproduction of food. the achievements of agriculture appear even more remarkable if one looks at employment. agriculture employed more than 75 percent of the total workforce in traditional agrarian societies, and, as late as 1950, about two - thirds throughout the world. nowadays, in the advanced countries, the share is about 2. 5 percent - - eleven million people out of 430. 6 in the rest of the world, agricultural workers still account for almost half the labor force, with a


thirds throughout the world. nowadays, in the advanced countries, the share is about 2. 5 percent - - eleven million people out of 430. 6 in the rest of the world, agricultural workers still account for almost half the labor force, with a world total of some 1. 3 billion workers ( 775 million in china and india alone ). such a massive transfer of labor, one of the key features of modern economic growth in the past two centuries, was made possible by a dramatic increase in product per worker. in short, agriculture is an outstanding success story. its achievements have been outshone by the even faster growth of industry and services, but the latter would have been almost impossible if the workers had not had sufficient food to eat. the aim of this book is to describe this success, and to understand its causes. chapter 2 illustrates the peculiarities of agriculture. its production depends on the environment : soil, climate, and the availability of water have always determined what peasants could grow, how much they had to work, and how much they could obtain from their efforts. these constraints have been relaxed in recent times, without totally disappearing. the factor endowment, and notably the amount of land per agricultural worker, determines the intensity of cultivation. the combined effects of the environment and the factor endowment have created long - lasting and area - specific patterns of land use, crop mix, and techniques ( " agricultural systems " ). the next three chapters present the main statistical evidence, loosely arranged in a production - function framework. chapter 3 deals with the long - term trends in output ( which has always been growing ), relative prices ( increasing in the first half of the nineteenth century, then roughly constant or slowly declining ), and world trade in agricultural products ( increasing quite fast before 1913 and again after 1950 ). the focus then shifts to the proximate causes of this growth, the increase in the use of factors ( chapter 4 ) and productivity growth ( chapter 5 ). historians have a fairly clear idea about the long - run change in factors. the total agricultural work force remained roughly constant all over the world, with the notable exception of western settlement countries ( north america, australia, argentina, and so on ) during settlement process - - that is, until the beginning of the twentieth century. the stock of capital grew fast beginning in the late nineteenth century, as machines substituted labor. although this conventional wisdom is not exactly wrong, it is, however, inspired a bit too much by the experience of the western world. the growth of land stock has been much


capital grew fast beginning in the late nineteenth century, as machines substituted labor. although this conventional wisdom is not exactly wrong, it is, however, inspired a bit too much by the experience of the western world. the growth of land stock has been much more geographically widespread and has lasted for longer than is commonly assumed. agricultural capital consists mainly of building, irrigation works, and the like, and thus it increased slowly but steadily throughout the period. the real process of mechanization started only in the 1950s, and the agricultural work force has gone on growing in absolute terms. thus, the growth of inputs ( extensive growth ) was the major cause of worldwide growth in agricultural production until the 1930s, but after world war ii, it slowed down. consequently, most of the big increase in total output in the past half - century has been achieved thanks to the growth in total factor productivity. the available estimates, surveyed in chapter 5, suggest that its growth has been increasing over time and that it has been faster in " advanced " countries than in ldcs. in the " advanced " countries, productivity growth has accounted for the whole of the increase in agricultural output. contrary to a common view, productivity growth has been faster in agriculture than in the rest of the economy, including manufacturing. chapter 6 focuses on the main source of this great achievement, technical progress. it starts by describing the main innovations, and then focuses on the process of their adoption. as in the rest of the economy, innovations are adopted when profitable, and profitability ultimately depends on the expected productivity gains and on factor endowment and factor prices. however, as the chapter argues, a standard neoclassical model cannot explain all the features of technical progress in agriculture. agricultural innovations depend on the environment and entail a high level of risk, and many of them yield little or no financial rewards to the inventor. these features call for a greater role of the state, both in the production and the diffusion of innovations. chapters 7, 8, and 9 deal with the institutional framework of agricultural production. " institutions " is a fairly vague word, which resists all attempts at a general definition. chapters 7 and 8 deal with property rights on labor and land, markets for goods and inputs ( labor, land, capital ), and agricultural co - operatives. chapter 7 is, to some extent, a general introduction to these issues and to the approaches of economists and historians to institutions. it discusses how institutions work and how they might affect the performance of agriculture. chapter 8 describes the main changes - - the creation of property rights


, to some extent, a general introduction to these issues and to the approaches of economists and historians to institutions. it discusses how institutions work and how they might affect the performance of agriculture. chapter 8 describes the main changes - - the creation of property rights on labor and land, the trends in the average size of farms, in landownership, and in contracts, and the development of markets for goods and factors. it also puts forward some tentative hypotheses on the likely causes of these changes and on their effects on agricultural performance - - although, it is fair to say, the discussion on these issues is surprisingly thin when compared to the attention they have received in the theoretical literature. chapter 9 focuses on the effects of agricultural policies. it argues that state intervention has only really affected agricultural development since the 1930s, and that, by and large, it has reduced the aggregate welfare of the whole population. the tenth, and last, chapter shifts the focus from agriculture to the whole economy. how did the growth of agricultural output and the change in input use affect modern economic growth? this issue has been the subject of much discussion in historical perspective, and it still looms large in the debates about the optimal development strategy for less developed countries. the chapter has no ambition to solve such a controversial issue. it sketches out the prevailing theories and deals very briefly with three case studies. the book closes with some very general remarks about the future of agriculture. the summary makes it clear that this is quite an ambitious book. it deals with many issues, and covers two centuries of agricultural history in the whole world, from monsoon asia to midwest prairies. any attempt to be comprehensive would be foolish. the potentially relevant literature spans dozens of languages, and many disciplines, from " traditional " agricultural economics and history to more " trendy " social and environmental history. just to quote an example, the fourth volume of a survey of agricultural economics literature, agriculture in economic development, contains more than two hundred pages of references. 7 assuming ( conservatively ) that there are twenty entries per page, the total sums up to almost four thousand entries. some of these works may be purely theoretical, and thus outside the scope of this book, but the majority should still be considered. the survey refers only to the less developed countries, deals ( almost ) exclusively with the post - world war ii period, lists only works in english, french, spanish, and portuguese published before 1990, and is probably, as with all surveys, not complete. a simple proportion suggests that there are thousands of potentially relevant


) exclusively with the post - world war ii period, lists only works in english, french, spanish, and portuguese published before 1990, and is probably, as with all surveys, not complete. a simple proportion suggests that there are thousands of potentially relevant references. clearly, no one in the world ( certainly not this author ) can reasonably claim to master all the literature. and even if this miracle were possible, it would be impossible to review it thoroughly and keep the book to a reasonable size. selective reading is an imperative. thus, i have decided to focus on more general contributions, and to favor works that frame their views in economic theory and buttress their statements with data. this approach has some clear and often rehearsed shortcomings. mainstream economic theory may appear too abstract to be relevant. agriculture is a highly local activity, and specialists in agrarian history always warn against broad generalizations, which, they claim, cannot capture the peculiarities of the area that they are dealing with. many data are missing, unreliable, or sometimes plainly wrong. reliable " historical " ( pre - 1950 ) data are available only for some " advanced " countries ( those of western europe, usa, japan, etc ). international organizations such as the un, fao, world bank, and the oecd have made a magnificent effort to extract comparable data for all countries from the information provided by national statistical offices, which are sometimes incomplete and / or of dubious quality. 8 however, there are some reasons for hope. modern development economics, with its emphasis on institutions, transaction costs, information, and so on, provides powerful tools for understanding rural societies, which can also be employed to explore societies of the past. economic historians have unearthed a great deal of new data, which, in spite of all their shortcomings, do throw light on many key issues. and, last but not least, i feel that there is no real alternative. a history of agriculture based on anecdotal evidence from local case studies would be a boundless and largely meaningless list of details. but details are sometimes fascinating and are useful for illustrating general points - - to put some flesh on the bare bones of quantitative analysis, so to speak. the reader may find the selection of these examples somewhat haphazard ( why - - for example - - discuss tenure in china during the 1930s instead of that in guatemala during the 1970s? ). it is, however, guided, whenever possible, by two principles : first, to deal with " large " countries ( china, india,


saturn ' s largest moon, titan, pictured to the right of the gas giant in the cassini spacecraft view. scientists have discovered methane lakes in the tropical areas of saturn ' s moon titan, one of which is about half the size of utah ' s great salt lake, with a depth of at least one meter. the longstanding bodies of liquid were detected by nasa ' s cassini spacecraft, which has been orbiting saturn since its arrival at the ringed planet in 2004. it was previously believed that such bodies of liquid only existed at the polar regions of titan. according to a report published in the journal nature, the liquid for the lakes could come from an underground aquifer. " an aquifer could explain one of the puzzling questions about the existence of methane, which is continually depleted, " said the lead author caitlin griffith. " methane is a progenitor of titan ' s organic chemistry, which likely produces interesting molecules like amino acids, the building blocks of life, " griffith noted. the lakes have remained since they were detected by cassini ’ s visual and infrared mapping spectrometer in 2004. only one rainfall has been recorded which shows that the lakes could not be replenished by rain. according to the theories regarding the circulation models of titan, liquid methane in the moon ' s equatorial region evaporates and is then carried by wind to the polar regions. methane is then condensed due to the colder temperatures and forms the polar lakes after it falls to the surface. " we had thought that titan simply had extensive dunes at the equator and lakes at the poles, but now we know that titan is more complex than we previously thought, " said linda spilker, a cassini project scientist. she further added that, " cassini still has multiple opportunities to fly by this moon going forward, so we can ' t wait to see how the details of this story fill out. " nasa launched the cassini spacecraft in 1997 and its mission has been extended several times, most recently until 2017.


west lafayette, ind. - parts of the human brain think about the same word differently, at least when it comes to prepositions, according to new language research in stroke patients conducted by scientists at purdue university and the university of iowa. people who speak english often use the same prepositions, words such as " on, " " in, " " around " and " through, " to indicate time as well as location. for example, compare " i will meet you ' at ' the store, " to " i will meet you ' at ' 3 p. m. " these examples show how time may be thought of metaphorically in terms of space. just because it ' s the same word, however, doesn ' t mean the brain thinks about it the same way, said david kemmerer, an assistant professor of psychological sciences and linguistics at purdue ' s college of liberal arts. " there has been a lot of cognitive neuroscience research about how the brain processes language pertaining to concrete things, such as animals or tools, " said kemmerer, who also is an adjunct faculty member at the university of iowa ' s department of neurology, where this research was conducted. " this is the first cognitive neuroscience study to investigate brain regions for spatial and temporal relations - those involving time - used in language. " i was interested in whether these spatial or temporal prepositions can be dissociated in individuals with brain damage. one might think that if a person ' s knowledge of the word ' at ' to describe location is impaired, then his or her ability to use that same preposition to describe time would be disrupted. but we found the words implying time are processed independently. " this research was conducted at the benton neuropsychology laboratory in iowa ' s carver college of medicine and was funded by the purdue research foundation and the national institute for neurological disease and stroke. kemmerer ' s paper is available online at neuropsychologia. " this study has potential implications for neurology, " kemmerer said. " a clinician could use information about how brain injuries in stroke patients affect specific speech components to develop therapies to help their patients. " the four patients in kemmerer ' s study were used because of similar brain injuries, such as lesions from stroke, in the perisylvian region, which is responsible for language processing. kemmerer found the stroke subjects who passed the language tests asking about prepositions relevant to time subsequently failed when these same words reflected spatial


, such as lesions from stroke, in the perisylvian region, which is responsible for language processing. kemmerer found the stroke subjects who passed the language tests asking about prepositions relevant to time subsequently failed when these same words reflected spatial meanings. for example, the subjects were asked to choose the correct preposition for scenarios such as, " the baseball is ' on / in / against ' the glove. " two subjects did not select " in " as the correct answer. however, they did select " in " as the correct preposition for " it happened ' through / on / in ' 1859. " the other two subjects ' test performances were the opposite. kemmerer ' s earlier research with daniel tranel, professor of neurology at iowa ' s carver college of medicine, had confirmed that the left inferior prefrontal and left inferior parietal regions of the brain play a crucial role in processing spatial prepositions. the previous research with tranel was published in october ' s cognitive neuropsychology. this work, which has explored how different types of words are retrieved by different parts of the brain, is part of a larger - scale investigation being carried out by tranel and his colleagues at the university of iowa. " for example, we have identified the anterior left temporal lobe as being critical for proper nouns, whereas the left inferior prefrontal / premotor region is important for verbs, " tranel said. " the collaboration between myself, a neuropsychologist, and professor kemmerer, a neurolinguist, has yielded important breakthroughs in understanding how the brain operates language, due to the unique perspectives that these researchers bring to a common research agenda. " three of the patients in kemmerer ' s recent study also had damage to their brains ' left hemispheres, in an area known as the parietal lobe, which houses the supramarginal gyrus. this area is involved in spatial meaning, and it is the part of the brain that guides action. for example, the supramarginal gyrus coordinates how a person moves his or her hand toward a glass of water. previous research with normal brains identifies this area as important also in the knowledge and meaning of prepositions. the patients with damage to the supramarginal gyrus did not score high on the tasks that evaluated their knowledge of prepositions that dealt with space. in comparison, the fourth patient, who did not have similar damage to


##s. the patients with damage to the supramarginal gyrus did not score high on the tasks that evaluated their knowledge of prepositions that dealt with space. in comparison, the fourth patient, who did not have similar damage to this region of the brain, was able to demonstrate complete knowledge of spatial prepositions. kemmerer ' s next step will be looking at how the brain processes these prepositions in other languages. " if this is true in english, then what about the 6, 000 other known languages in the world? this time - and - space metaphor is used from language to language, but how the metaphor is used does vary, " he said. in english, months of the year are treated as containers. people say " in january " or " in february. " other languages treat months as surfaces. for example, " on january " or " on february. " despite the difference, there is a metaphor at work, kemmerer said. " the cross - linguistic ubiquity of the metaphor suggests that people are naturally inclined to conceptualize time in terms of space, " he said. " nevertheless, the neuropsychological data suggest that people don ' t need to invoke the metaphor every time they use prepositions to talk about time. just as the word ' breakfast ' doesn ' t require one to think of a morning meal in terms of breaking a fast, so the sentence ' she arrived at 1 : 30 ' doesn ' t require one to think of time as a series of points on a line. " source : eurekalert & otherslast reviewed : by john m. grohol, psy. d. on 21 feb 2009 published on psychcentral. com. all rights reserved. great things are not done by impulse, but by a series of small things brought together. - - vincent van gogh