# Philosophical Works of the Late James Frederick Ferrier/Lectures on Greek Philosophy (1888)/The Pre-Socratic Period - Introductory

Lectures on Greek Philosophy, Philosophical Works of the Late James Frederick Ferrier (1888 ed., Vol. 2). (E. L. Lushington, & A. Grant, Eds.) Edinburgh: William Blackwood and Sons. pp. 1-33.
GREEK PHILOSOPHY.
I. THE PRE-SOCRATIC PERIOD.
INTRODUCTORY.
1. In the present session I propose to treat of the history of Philosophy, both moral and metaphysical, on a more extended scale than I have yet been in the habit of doing. Philosophy itself must, of course, engage our attention; because, unless we know what philosophy is, unless we have a clear conception of its aim and results, the history of philosophy must remain a blank, a sealed book, a mere repertory of dead and unprofitable dogmas. But when we have once formed a right conception of philosophy, the study of its history will then be found to react powerfully in confirming and enlarging our knowledge, and in directing and enlightening our energies. The aim of philosophy is to raise us into the region of universal, or, as I may call it, unindividual, thinking; the accidents of reason must fall away, and the ​essence of reason must stand forth declared: all that is arbitrary in human thought must disappear; and we must rest on the necessary elements of mind and of the universe. That is the end which philosophy proposes to her votaries, because it is only through this abnegation of particular or optional thinking that universal truth can be attained. This is the end which, on a small scale, must occupy the individual thinker; it is the end which, on a large scale, has occupied all the generations of philosophers from the dawn of speculation until now. Hence, in studying the history of philosophy, we shall find that we are in fact studying only the development of our own reason in its most essential forms, with this difference, that the great problem which, in our minds, is worked out in a hurried manner, and within contracted limits, is evolved at leisure in the history of philosophy, and presented in juster and more enlarged proportions. The history of philosophy is in fact philosophy itself taking its time, and seen through a magnifying-glass.
2. The chief aim of the historian of philosophy ought to be, to give a continuity or organised connection to the different parts of his narrative. But to do this, he must endeavour to verify in his own consciousness, and as the indigenous growth of his own mind, the speculations of antecedent thinkers. He may not agree with these speculations; but he ought, above all things, to understand what they mean—what they are in their spirit, and not merely ​in the letter. When I say that he must verify these doctrines in his own consciousness, I mean that he must actively reproduce and realise them in his own thoughts, together with the grounds on which they rest. He must be able to place himself in the mental circumstances in which they arose, and must observe them springing up in his own mind, just as they sprang up in the minds of those who originally propounded them. They must be to him, not the dead dogmas of their thinking, but the living products of his own. They must come to him not as antiquated traditions, but as teeming with present interest, and as fraught with a present and inextinguishable vitality. As an original thinker, he must reanimate these doctrines from within, while, as a critic and historian, he is engaged in receiving and deciphering them from without. What he receives from others he must also find as the indigenous growth of his own mind. What he must be able to say to himself is this: Such a system, or such a doctrine, or such a problem, is not what some individual thinker has chosen to think, or has accidentally thought, but it is what thinking itself, in certain circumstances, must inevitably think. It is only when he conceives and executes his vocation in this spirit that the historian of philosophy can be regarded as having verified and reanimated the systems which he is expounding. When he has so verified them—verified them in the manner thus imperfectly described—he has obeyed the primary obligation by which the historian of ​philosophy is bound, and has fulfilled a requisition which either contains all other rules, or renders all other rules superfluous.
3. In the older histories of philosophy this rule is but little attended to, this obligation is very imperfectly fulfilled. They abound in learning, but they are lamentably deficient in insight. They are in general mere repertories of disjointed and exploded opinions, of capricious and arbitrary thoughts, which, as presented in these compilations, contain no point of interest for any living soul. The letter is there, but the spirit has altogether fled; there is abundance of the husk, but the kernel is nowhere to be found.
4. Of late years the history of philosophy has been studied in a profounder and more rational spirit. Living insight has been aimed at rather than dead learning. Attempts have been made to grasp the inner soul rather than the external environment of bygone speculations, and to trace the logical filiation of systems. These attempts, it must be owned, have been only partially successful. Much still remains to be done. The ground has been broken; but it cannot be said that the jungle has been cleared, or the roads made. The most diligent pioneers in this good work have been the two German philosophers, Hegel and Zeller. But Hegel's work on the history of philosophy labours under the disadvantages incident to a posthumous publication, and seems in many ​places to contain mere hints which probably were more fully expanded in the oral delivery of his lectures. Much of it may be described as made up of dark, abrupt, and laconic jottings. Zeller's history of the Greek philosophy is in some respects more complete, and is indeed a very valuable work: but it is too much pervaded, particularly in those places where clearness is most required, by that obscurity, indeed I may say unintelligibility, which seems to be inseparable from the philosophical lucubrations of our Teutonic neighbours. With all these shortcomings, however, I am of opinion that these two historians of philosophy, Hegel and Zeller, are entitled to take precedence before all other inquirers in this difficult field of research.
5. To enable the historian of philosophy to enter on his work with any chance of success, we have now to consider what equipment he requires—requires on his own account, and also on account of those whom he addresses. We have to consider what preliminary study he has to go through before he can prosecute his researches successfully, and what preparatory information he must lay before his audience before he can expect to render intelligible to them the result of those researches. It is principally, I think, in regard to this preparatory or introductory matter that all the histories of philosophy are wanting; and it is for the purpose of supplying this defect, and of remedying it in so far as I can, that I proceed to speak of ​what I conceive to be the essential preliminaries to the study of the history of philosophy.
6. The essential preliminary to the study of the history of philosophy is, a clear conception of philosophy itself. Without this the history of philosophical systems cannot be studied to much—or, I would rather say, to any—advantage. It may be thought that philosophy itself is best learned from the study of its history: and there can be no doubt that the latter reacts upon the former in the way of rendering our conception of philosophy more definite, as well as more comprehensive. The conception of philosophy is confirmed and enlightened by the survey of philosophical systems. But without some tolerably definite conception of what philosophy is, and of what it aims at, the study of these systems is a vain and unprofitable pursuit. We must have this conception to begin with—we must have it to found upon—otherwise we cannot expect to derive any intellectual improvement from the study of the history of philosophy; we shall be baffled and bewildered at every turn by the apparent extravagances and unintelligibilities which we encounter. Even when we carry with us a clear conception of philosophy, we are frequently perplexed when tracing historically the mazy windings of speculation; but without this clue we should be utterly lost and confounded.
7. What, then, is the conception of philosophy? ​I cannot tell you this in one word or in one sentence. We must make our approaches to it gradually, beginning with what is very indefinite, and making it more definite as we proceed. Let us begin, then, with a definition, which, though it conveys very little in-formation, is quite unexceptionable—is, indeed, what the whole world is willing to assent to—and let us say that philosophy is the pursuit of truth. This is the first, and simplest, and vaguest conception and definition of philosophy which we can form.
8. This definition calls for some explanation as to what we mean by truth. When we say that philosophy is the pursuit of truth, we must at any rate have some notion of the object of which philosophy is the pursuit. What, then, do we mean by truth? I commence by calling your attention to a distinction by means of which we may clear up our idea of truth, and bring ourselves to understand what it means; I refer to the distinction of truth into truth relative and truth absolute. When I have explained what these two kinds of truth are, we shall then be able to render our definition of philosophy more distinct and complete by declaring whether philosophy be the pursuit of truth relative or of truth absolute. I proceed, then, to speak first of relative truth, and secondly of absolute truth.
​10. Secondly, of truth as absolute. As relative truth is truth which is true for one mind, or for one order of intelligence, so absolute truth is truth which is true for all minds, for all orders of intelligence. It is plain that absolute truth cannot mean truth placed altogether out of relation to intelligence, for that would be equivalent to saying that the highest truth could not be apprehended by the most perfect intelligence, not even by omniscience. To define absolute truth as that which stands out of relation to all reason—as that which is not to be known on any terms by any intelligence—is a position too absurd to require any exposure. All truth, therefore, is in this sense relative, that is, can be conceived only in relation to intelligence; but the distinction between absolute truth and relative truth is, as has been stated, this: that relative truth is what exists only for some, but not necessarily for all minds; while absolute truth is that which exists necessarily for all minds. We shall find hereafter that this distinction is of great service to us in leading us to understand the grounds upon which philosophers generally have set so little store on the truth of our mere sensible impressions. No philosopher ever denied that the intimations of the senses are relatively true, or that we should place implicit confidence in them as presentations relatively true. But many have denied that these intimations were absolutely true, were valid of necessity for all minds. The grounds, however, on which those philosophers proceeded, have ​been frequently mistaken. Hence many perplexities have arisen, and hence speculative thought has been often unjustly charged with inculcating absurdities, which existed nowhere except in the misapprehensions of its accusers.
11. Having thus explained and defined (intelligibly, I trust, though not fully, and perhaps not convincingly) the distinction between relative truth and absolute truth, we have now to ask, Which of these two forms of truth is the special object of philosophy? The answer is, that the attainment of absolute truth, of truth as it exists for all intellect, is the principal, though not the exclusive, aim of philosophy. Philosophy must not overlook altogether the consideration of relative truth, because perhaps a finer analysis will show us that the two are ever blended together in an essential and inseparable contrast. But nevertheless, as I have said, absolute truth is the principal, indeed the proper, object at which philosophy aims; it is the point at which all the higher metaphysicians of every age and of every nation have aimed, and at which it is their duty to aim (however far short of the mark their efforts may be doomed to fall), if they would continue true to their vocation.
12. A question here arises which threatens to cut short our progress: Are man's faculties competent in any degree to the attainment of absolute truth? ​The whole prospects of philosophy, according to the conception of it which we are endeavouring to fix, are obviously involved in the answer to this question. If we reply peremptorily that man's faculties are in no degree competent to the attainment of absolute truth, our discussion is at once cut short, and our conception of philosophy is annihilated. Such is the result if we answer this question in the negative. Therefore, while I admit the difficulty and the importance of the question, I am constrained to answer it in the affirmative, although I cannot at present set forth fully the grounds of my decision. I answer it in the affirmative with this proviso—a proviso which may perhaps save me from the charge of speaking too dogmatically—and I say that man's faculties are competent to the attainment of absolute truth, provided and in so far as man's mind has something in common with all other minds; in other words, provided there be a universal intelligent nature in which he is a partaker. It is obvious that this community of intellectual nature is the ground, and the only ground, on which man can lay claim to any knowledge of the absolute truth, because absolute truth has been defined as that which exists for all minds; but unless man's mind has something in common with all minds, absolute truth cannot exist for him, can have no meaning in reference to him; while, on the other hand, if he has something in common with all other intelligences, he may lay claim to an interest ​in absolute truth, and is competent to attain to it when the requisite exertions are put forth.
13. You thus perceive that the question regarding our competency to attain to absolute truth resolves itself into the new question, Is there in the mind of man a universal part—that is, a part which in all intelligences is essentially of the same character? Intelligence itself seems to constrain us to answer this question in the affirmative. That there is such a part seems to me to be an axiomatic truth of reason. To suppose, for example, that the supreme intelligence has nothing whatever in common with the human intelligence, is to suppose that the one of them is an intelligence, and that the other is no intelligence at all. It is to dissolve the very ground on which we conceive both of them as intelligences. Two intelligences which have nothing whatever in common cannot both of them be intelligences; they cannot be both placed under that category of thought, or indicated by the one word intelligence, because it is only through our thought that they possess some point or quality in common that we can think of them as intelligences; and therefore, to think of them as having no common quality, and at the same time to think of them as intelligent, is to think of them as both having, and as not having, something in common; in other words, it is to think a downright contradiction. This truth, then, in regard to the constitution of the human minds, and of all ​minds, namely, that they agree in some respect, seems to be a necessary axiom of reason. In all intelligence there is, by the terms of its conception, a universal, that is, an essential unity of kind, however small the point of unity may be.
14. On religious grounds this unity might be much more largely insisted on. Its postulation is the very foundation and essence of religion. This unity constitutes the very bond, and the only bond, between the Creator and the creature. Deny this connection between the divine and the human reason, and you destroy the very possibility of religion.
15. I admit, however, that the answer which I have ventured to return to this question, is one which cannot be expected to command your assent until you have time to reflect upon it more fully, and it is well worthy of your most attentive consideration. It is indeed the question of the present day, as it was the great question of philosophy in the time of Socrates and the Sophists. The whole sophistical philosophy proceeded on the assumption that there was or might be, an absolute diversity of kind in the constitution of intellectual natures; that different orders of minds had not necessarily anything whatsoever in common. From whence it followed that there were as many kinds of truth as there were kinds of mind, quot mentes, tot veritates; in other words, that there was no truth at all, no absolute ​truth, no truth, in the strict sense of the word, anywhere in the universe. In these few words are contained the sum and substance of the sophistical philosophy, and the arguments by which Socrates endeavoured to rebut the conclusions of the Sophists proceeded on no other principle than that which I have attempted to place before you; the principle, namely, that there is a common nature, known by the name of reason, in all intelligent beings; and that, in virtue of this common nature, man can rise to some extent to the contemplation of absolute truth, which exists, and can exist, only as the counterpart and object of this common reason, of which man, in his degree, is a partaker.
16. But my object at present is not so much to settle the question in regard to the unity or common nature of intelligences, as to place before you a clear conception and precise definition of philosophy, a conception and definition which may be of service to us when we come to deal with the history of speculative systems. I defined philosophy at the outset as the pursuit of truth. I now define it as the pursuit of absolute truth; and farther, having defined absolute truth to be truth as it exists for all minds, I add that circumstance to the definition, and I affirm that "philosophy is the pursuit of absolute truth, that is, of truth as it exists for all intelligence."
​17. What I wished principally to impress upon you in my last lecture was, the distinction between relative truth and absolute truth. All truth is, in one sense, relative; that is to say, whatever we know or think of must be known or thought of in relation to ourselves. All that we know must be known in conformity with our capacities of knowledge, and cannot be known except under the conditions imposed by these capacities. But here is where the distinction lies: relative truth is truth which comes to us in virtue of our particular nature as human intelligences; absolute truth is truth which comes to us in virtue of our common nature, as intelligences simply, what is here looked to being merely the circumstance that we are intelligences at all, and not the circumstance that we are this or that particular kind or order of intelligence. Let us suppose a number of intelligences divided into different kinds, into various orders and degrees; you will observe that, by the ordinary logical doctrine, each of these kinds must embrace something peculiar to itself, and also something common to the whole number, however numerous the classes of intelligences may be. Now, what I want to impress upon you is this: that each of these kinds of intelligence will know and apprehend partly in conformity with the peculiar endowment of what I have spoken, and partly also in conformity with the common endowment of which I have spoken. And what it apprehends in conformity with its peculiar capacity is relative truth; what it ​apprehends in conformity with its common capacity is absolute truth. It is further obvious from this explanation that relative truth is, as I have already frequently said, truth merely for some minds; while absolute truth is truth for all intelligence: and this analysis of the mind into a common capacity and a peculiar capacity, furnishes us, we shall by-and-by see, the true ground of the well-known distinction of the human faculties into sense, understanding, and reason.
18. To return to our definition of philosophy: Without altering the meaning of that definition, I may slightly vary its expression; for ideas sometimes gain in distinctness by being presented under different forms of expression. Truth, we may say, is that which is—it is the real; so that, instead of saying that philosophy is the pursuit of absolute truth, that is, of truth as it exists for all intelligence, we may say that "philosophy is the pursuit of the absolutely real, that is, of the real as it exists for all intelligence." These two expressions are synonymous; but, perhaps, to some of you the latter form of the definition may be the more significant of the two.
19. This definition may be open to objections; but I cannot think that it is open to any well-founded objections. As objections, however, are actually urged, which are very pertinacious, if not very strong, some notice must be taken of them. They are so obtrusive, and they have carried with ​them so much apparent weight, that the dominant philosophy of this country is founded upon a denial and repudiation of the definition which I have ventured to lay down as the only true definition of philosophy. In direct contravention of this, high authorities have maintained that philosophy is the pursuit of mere relative truth, of truth as it exists, not for all, but only for our intelligence. And they found this definition on the consideration that man can deal with truth only as it presents itself to his particular mental constitution. Their own doctrine and their objection to our position may be summed up under the following query, which they address to us: How is it possible for man to know or to speak of any truth, except such as exists for his particular intelligence? How can he have anything to do with truth? What can he know about truth as it exists for all intelligence?
20. I answer, that man can have nothing to do with truth as it exists for all intelligence, can know nothing at all about it, unless there be something in his intelligence which links him to all intelligence; some point or quality in which his intelligence agrees with all other intelligences; in short, unless there be a universal or common nature in all intelligences. If there be this, if intelligence be to some extent universally the same, then it is obvious that man can know the truth as it exists for all intelligences; for he has merely to look to the truth which addresses ​itself to the universal part of his own intelligent nature; this universal part being the same in all, the truth which it apprehends must be the same for all; in other words, that which it apprehends must be the truth for all intelligence, and not merely the truth for man's intelligence; it must be absolute and not mere relative truth. On the other hand, if it be true that there is no common nature, no universal faculty in all intelligence, no point in which all minds agree; in that case it must be admitted that the objection is fatal to our definition of philosophy. In that case man can have no dealings with absolute and universal truth; the only truth of which he can be cognisant must be relative and particular. But observe the contradiction in which we get involved if we take up this position. I have already stated what this contradiction is, and therefore I merely repeat my statement, that if we deny to intelligences a common nature in which they all participate, or if we deny to man's intelligence a participation in this common nature, we fall into the absurdity of at once including certain things under the same category of thought, and of excluding at the same time some of these things from that category.
21. My object at present is rather to furnish insight than to inspire conviction. I wish you rather to understand what I say, than to be convinced by what I say; and I think you may now understand distinctly the positions respectively occupied by the ​two parties who divide the philosophical world. On the one hand, we have those whom I venture to regard as the true philosophers. They hold, first, that there is some principle or quality or faculty common to all intelligence; and, second, that in virtue of this common faculty man is competent, to some extent, to apprehend the truth as it exists for all intelligence; in other words, is competent to apprehend the absolute truth. And founding on these two postulates, they obtain such a definition of philosophy as that which I have given you—a definition which follows at once from these two postulates, namely, that philosophy is the pursuit of the absolute truth, or of the absolutely real; that is, of the true and real as they exist for all intellect. On the other hand, we have those whom I venture to regard as the opponents of true philosophy. They hold, first, that there is no principle or quality or faculty common to all intelligence; and, secondly, that in consequence of there being no such universal principle, man is not competent to apprehend the truth as it exists for all intelligence; in other words, is not competent to apprehend the absolute truth: and founding on these two postulates, they obtain the following as their definition of philosophy—Philosophy is the pursuit of mere relative truth, or of the relatively real; that is, of the true and real as they exist merely for man's intelligence.
22. You have now before you the two definitions ​which express the two conceptions that lie at the root of the two great schools of philosophy that have divided the world, and two more fundamental conceptions of these antagonist philosophies I believe it is not possible to obtain. I have called both of these schools philosophical; but in strict speech we ought to say that while the one of them is philosophical, the other is anti-philosophical, for they are directly opposed to each other, as you may see from the opposite conceptions which each of them entertains in regard to the proper business of philosophy. But we need not quarrel about the use of a word; and, provided the opposition between the two parties be understood, we may apply the term philosophical to both of them.
23. But to render our definition of philosophy complete, something, indeed a good deal, still requires to be added to it. Philosophy, I have said, is the pursuit of the real as it exists for all intelligence. This definition proceeds, as I have said, on the postulate—a postulate which I regard as axiomatic—that all intelligences know and think in some respects alike. It is not necessary, at present at least, to suppose that there are more intelligences than ours in the universe; but if there are other intelligences, it is necessary to suppose that they agree in some respect with ours, or, in other words, that all intelligences, actual or possible, have something in common. Now, the question here arises, What is ​this universal principle, this faculty which is common to all minds, in virtue of which we are able to apprehend the truth, not merely as it exists for us, but as it exists for all? What can we say in explanation of this faculty?
24. To explain this universal faculty, I shall bring forward a few illustrations as the best means of rendering myself intelligible; or rather, without assuming that we have such a faculty, I shall produce the grounds which compel us to hold that there is something universal, as well as something particular, in our intelligent constitution. When I apply sugar to my palate, and declare that the taste is sweet and agreeable, am I entitled to declare further that sugar is sweet and agreeable to all sentient and intelligent beings? Can I announce this as a truth for all intelligence? Obviously I cannot; and why can I not? Simply because I am under no compulsion so to regard it: I can help thinking it as a truth for all intelligence. And on what ground can I help so thinking it? On the ground that an intelligence with a different organism from mine would apprehend the sugar differently. Therefore the truth for me, namely, that sugar is sweet and agreeable, cannot be laid down as a truth for all intelligence. Take another case. I say," The earth goes round the sun." Is that a truth for all intelligence? It looks very like one, but it is not one. And why not? you will ask. I answer, for this reason: that a truth for all ​intelligence means a truth which is valid for all intelligences which may have existed in the countless ages of the past, or which may exist in the countless ages of the future. Now, I am under no compulsion to think that the earth from all eternity has revolved around the sun, or that it will continue throughout all eternity so to revolve around the sun; in other words, I can help thinking that it always has travelled, and that it always will travel, as it now travels. I can conceive the operations of the universe changed. This, therefore, is not a truth valid at all times for all intelligence. Take another case. I say, The square on the hypotenuse of a right-angled triangle is equal to the squares on the other two sides; or, to take a simpler case, I say that two straight lines cannot enclose a space. Are these truths which exist for all intelligence? Yes, they undoubtedly are. Take the former: it is a truth which is valid for all intelligence. And why do I so regard it? Simply because I am compelled. I cannot help thinking it as a truth which every intelligence which follows the demonstration must assent to. And why can I not help thinking it to be a truth of this character? Because I cannot conceive that any difference in the organism, or any difference in the constitution of the universe, or any difference in the intelligence which apprehends it, should cause it to be apprehended differently. I cannot conceive any mind which understands the demonstration to hold that the squares on the two sides are either greater or less than the square on the third ​side; and therefore I maintain that this is a truth valid not only for any intelligence, but valid for all intelligence; and that all mathematical truth, from the simplest axiom up to the most recondite conclusions, is of this character.
25. These observations (which have been somewhat hastily thrown together) are designed to contribute towards establishing this great and important conclusion, that the mind of man consists of a universal part as well as of a particular part, or of what we may call a universal faculty and a particular faculty. To pave the way for a right understanding of this distinction, I adduced these illustrative truths. The first was the truth that sugar is sweet; the second was that the earth goes round the sun; the third was (to take the simplest of the two cases) that two straight lines cannot enclose a space. Now, I have shown you that the first and second of these truths cannot be said to be true for all intelligences; and I have assigned the reason of this, which is, that either the constitution of the person who apprehends them, or the constitution of nature, can be conceived to be changed in so far as regards these truths, and that with the change, either in the constitution of the person or in the constitution of nature, the truth would cease to be true. Therefore they are particular and relative. I have further shown you that the third of these truths can be declared true for all intelligence, because no change in the constitution of the ​person who apprehends it, no change in the constitution of nature, can in any degree affect it. This truth, then, that two straight lines cannot enclose a space, is universal and absolute. Thus we have two sorts of truths; a particular order, comprising all the truths represented by our first and second truths, and a universal order, comprising truths represented by our third truth. The particular order may be described as consisting of truths for some, but not for other, not for all, intelligences. The universal order may be described as consisting of truth for all intelligences.
26. What I have now particularly to call your attention to is, that just as there is one order or form of truth which is particular, and another order which is universal, so there is a faculty in man which is particular, and a faculty which is universal. The difference in the truths justifies us in maintaining a difference in the faculties or organs by which they are apprehended. We do not begin by finding that the mind has different faculties, but we begin by finding that the truths which the mind apprehends are very different in their character; that some of them are particular and relative, are truths merely for us; while others of them are universal and absolute, are truths for all intelligence; and in virtue of the objective distinction, as we may call it, we postulate a subjective distinction in the mind which apprehends them. We declare that, in reference to the particular ​truths, man has a corresponding particular faculty; and in reference to the universal truths, that he has a corresponding universal faculty.
27. This analysis I regard as the most fundamental distinction which can be drawn in the science of the mind. It lies at the root of the ordinary division of the mind into Sense, Understanding, and Reason. If you were asked in what do these three differ, you would find it difficult to return a perfectly satisfactory answer. In regard more particularly to understanding and reason, you would find yourselves at a loss; for the difference between these two is what no psychology has as yet succeeded in explaining. But say that reason is the universal faculty, the faculty of truth as it exists for all intelligence, and that sense and understanding are divisions of the particular faculty, that is, of the faculty of truth as it exists for some, but not for all intelligence, and light breaks in upon the distinction. You perceive that the faculty which is conversant with truth for all must be different from the faculty which deals merely with truth for some; and perceiving that, you obtain an insight into the distinction between sense and understanding on the one hand, and reason on the other hand; you begin to comprehend something of the constitution of your own mind, and also of mind universally.
28. I have just one more remark to make before I expand my definition of philosophy, by means of ​what I have said in regard to the universal faculty in man. It is obvious that this faculty must be the power, or seat, or place of necessary thinking, that is, of thoughts which we cannot help thinking, thoughts of which the opposites are pure nonsense; and in like manner it is obvious that the truths with which this faculty deals must be necessary truths, truths which cannot help being as they are, truths which cannot be otherwise than they are, and the opposites of which are pure nonsense. There is thus an objective necessity in truth, and a subjective necessity in thought, and the one of these corresponds to the other. For example, we say it is an objective necessary truth that two straight lines should not be capable of enclosing a space. And we say it is a subjective necessary thought that two straight lines should not be thought capable of enclosing a space. But what you have chiefly to attend to is, that wherever a necessary truth is apprehended, a truth which cannot be otherwise than it is, there the faculty of necessary truth, the universal faculty, comes into play, there necessary thinking takes place, there we think a thought which we cannot help thinking.
29. These considerations enable me to add something to my definition of philosophy, and to give it out in the following terms, which are the most definite, as well as the most complete, which I can at present devise. Philosophy is the pursuit of absolute truth, or of the absolutely real, that is, of the true and ​real as they exist for all intelligence; and this pursuit is conducted under the direction of the universal faculty in man, or, in other words, is conducted under the direction of necessary thinking.
30. If you attend to the definition of philosophy which I have given you, you will perceive that it comprehends two important points: it states both what the truth is which philosophy pursues, and what the faculty is which is engaged in the pursuit. The first part of the definition declares what the truth is which philosophy pursues: it says that philosophy is the pursuit of absolute truth, that is, of truth as it exists for all intelligence. This may be called the objective part of the definition; it declares what is the proper object of philosophy. But the definition would be incomplete unless we added something in explanation of the faculty by means of which the object of philosophy is to be attained. Therefore we subjoin:—And this pursuit is conducted under the direction of the universal faculty in man; in other words, is conducted under the direction of necessary thinking. Man's faculty of necessary thought is properly called his Reason. So that the definition expressed shortly is this: Philosophy is the pursuit of absolute truth conducted under the direction of reason. But the definition under this compendious form expresses a mere vague truism unless you keep in mind what we mean by absolute truth, and also what we mean by reason. ​31. There is one difficulty which this definition leaves unresolved, and that is the question, Whether the truth of which philosophy is the pursuit be a kind of truth or an element of truth; in other words, whether absolute truth can be apprehended by itself, or whether it must always be apprehended in union with relative truth? In short, whether each, the absolute and the relative, is a form of truth which can be apprehended without the other, or whether each can be apprehended only in combination with the other? This question I have considered under Proposition VI of my 'Institutes of Metaphysic,' where I have stated my own opinion, that the two must always be apprehended together. But as this is a point which can be settled only as the result of our researches, and as the whole history of philosophy shows that it is a very undecided question, I think it better to make no allusion to it in the definition, but merely to affirm that absolute truth is the object of philosophy, without saying whether absolute truth is a kind or is an element of truth. And, in the same way, I do not at present discuss or decide the question, whether reason be itself a faculty or merely an element of a faculty, sense being the other element which goes to make up the completed faculty.
32. Philosophy having been thus defined, we are now in a position to define the history of philosophy. This definition is very easily given—it follows as a matter of course. If philosophy be the pursuit which ​I have described, the history of philosophy must be the history of that pursuit, and accordingly we define the history of philosophy as the history of the pursuit of absolute truth, or of truth as it exists for all intelligence; and the history, moreover, of this pursuit, as conducted under the direction of the universal faculty in man, that is, under the direction of necessary thinking, or, more shortly, of reason.
33. These preliminaries being understood, the historian of philosophy ought now to have a tolerably distinct conception of the work which he has to take in hand. The task which he has to undertake is now apparent, although it may be beyond his power to execute that task even moderately well. It is obvious that the great business of the historian of philosophy must be to note and to point out how, and to what extent, philosophy, as manifested in its history, corresponds with philosophy as laid down in its definition. It is obvious that if philosophy, as manifested in its history, does not correspond at all—indeed, unless it corresponds to a very large extent—with philosophy as laid down in its definition, the definition must be false. It is incumbent, therefore, on the historian of philosophy to show this correspondence. This is the principal work he has to perform. He must be able to show that the spirit of speculative inquiry when looked at in itself, is borne out by the spirit of speculative inquiry when looked at in its historical progress.
​34. The definition of philosophy thus expresses the bond of union which unites the different systems, and serves as a clue by which the progress of the historian may be directed. The historian may sometimes lose sight of this clue, at other times he may perceive it very indistinctly, but in general he will be able to trace it as a fine thread running through and binding together the different systems which come under his inspection. The clue, in short, on which he must fix his eye, is the circumstance, that the truth which philosophical systems aim at is absolute, and not relative, truth; that is to say, is truth as it exists for all, and not truth as it exists merely for some, intelligence.
35. The difficulty of following out this principle must be confessed to be great; and this difficulty arises mainly from the fact that the philosophers whose system we have to examine and estimate, never distinctly realised, or held clearly before their minds, that conception of philosophy which is expressed in our definition. Hence they frequently appear to be engaged in researches which have little or no connection with that pursuit which we have defined as the proper vocation of philosophy. They frequently appear to reach results which fall very far short of the absolute truth, results very different from those which we might expect philosophers to place before us. They frequently appear to entertain the most wayward and capricious opinions, instead of being ​guided by the strict necessities of reason. But if we keep in mind this consideration, that the moving forces of speculation, as of everything else, operate secretly long before they openly show themselves, we shall not consider it surprising that the outward expression of philosophy should often differ extremely from its inward spirit; that its invisible life should often find a very inadequate exponent in its visible form; that the written letter should often indicate very imperfectly the unwritten meaning. It has only been by slow degrees that the mind of man has attained to a distinct consciousness of the right conception of philosophy as the pursuit of truth as it exists for all intelligence, and to the right conception of the means to be employed in that pursuit, namely, necessary thinking. Yet there is sufficient evidence to show that both of these conceptions were at the bottom of the endeavours of the very earliest philosophers, and were the animating principle of their researches.
36. Nothing is more perplexing to the student of the history of philosophical systems than the opposition to his ordinary modes of thought which these systems usually present. They seem quite alien from his ordinary ways of thinking. Their thoughts are not as his thoughts, and he cannot understand how their views of things should be so different from his. The explanation is, that while he is imbued with truth as it exists for his mind, with relative truth ​appealing to the particular part of his nature, these systems are aiming at the attainment and exhibition of truth as it exists for all minds, of absolute truth, appealing to the universal part of man's nature. In these attempts they may be far from successful; but knowing what their aim is, and knowing that there must be a difference between truth considered as universal and absolute, ultimate and elementary, or truth as it is for all, and truth particular, relative, or as it is for some, we are in a position to comprehend their drift and scope; and although they may fail to convince us, we shall in general be able to understand them.
37. For example, throughout the whole history of philosophy we find sensible knowledge held in but slight esteem. The truths of the senses are denied to be truths at all in the proper and strict acceptation of the word truth, and we are referred away to some other form of truth, of which no very clear account is given. To the young student of philosophy this is a most disheartening and perplexing procedure. He cannot understand why the truths of sense should be set aside as of little or no account, and why another set of truths, which seem to him far less satisfactory, should be brought forward in their place. And in no work, either on philosophy or on its history, does he find any very satisfactory reason assigned for this preference. But let him be told, and let him be called upon to consider, that the truths of ​the senses are not necessarily truths for all minds, but only truths for beings with senses like ours—are, in fact, only truths for some intelligences; and let him be further told, that the truth which philosophy aims at is the truth as it is for all intelligences; and he will be no longer surprised at the disparaging tone in which sensible truth is spoken of in the history of philosophy. He may be of opinion that philosophy is wrong in this, inasmuch as he may think that all truth for man resolves itself into mere sensible truth. But whether philosophy be right or wrong, the student now understands distinctly the ground on which philosophy proceeds in holding as of little or no account the knowledge which comes to man through the senses. He sees that the reason why philosophy undervalues sensible knowledge is, that such knowledge is the truth only for some, but not for all intelligence. And he sees, further, that philosophy, if she is to be true to the terms of her own definition, not only may, but must, affix a brand on all sensible knowledge, stamping it as comparatively invalid and irrelevant.