PLASTIC denotes a thing endowed with a formative power, or a faculty of forming or fashioning a mass of matter after the likeness of a living being.

Plastic Nature, a certain power, by which, as an instrument, many philosophers, both ancient and modern, supposed that the great motions in the corporeal world, and the various processes of generation and corruption, were perpetually carried on.

Amongst the philosophers of Greece, such a power was almost universally admitted. It seems, indeed, to have been rejected only by the followers of Democritus and Epicurus, who talk as if they had thought gravity essential to matter, and the fortuitous motion of atoms, which they held to have been from eternity the source, not only of all the regular motions in the universe, but also of the organization of all corporeal systems, and even of sensation and intellection in brutes and in men. It is needless to say, that those men, whatever they might profess, were in reality atheists; and Democritus, it is universally known, avowed his disbelief of a God.

The greater part of the philosophers who held the existence of a plastic nature, considered it not as an agent in the strict sense of the word, but merely as an instrument in the hand of the Deity; although even amongst them there were some who held no superior power, and were of course as gross atheists as Democritus himself. Such was Strato of Lampsacus, a man originally of the peripatetic school, over which he presided many years, with no small degree of reputation for learning and eloquence. He was the first and chief asserter of what has been termed līylo-zoic Atheism ; a system which admits of no power superior to a certain natural or plastic life, essential, ungenerated, and incorruptible, inherent in matter, but without sense and consciousness. That such was his doctrine we learn from Cicero, who makes Velleius the Epicurean say, “Nec audiendus Strato qui Physicus appellatur, qui omnem vim divinam in Natura sitam esse censet, quae causas gignendi, augendi, minuendive habeat, sed careat omni sensu.”^[1. Natura Deornm, lib. i. cap. 13. ] That Strato, in admitting this plastic principle, differed very widely from Democritus, is apparent from the following account of him by the same author: “Strato Lampsacenus negat opera deorum se uti ad fabricandum mundum; quaecunque sint, docet omnia esse effecta naturae, nec ut ille, qui asperis, et levibus, et hamatis uncinatisque corporibus concreta haec esse dicat, interjecta inani; somnia censet haec esse Democriti, non docentis sed optantis.”^[2. Qnoest. Acad. lib. iv. cap. 38. ]

That the rough and smooth, the hooked and crooked, atoms of Democritus, were indeed dreams and dotages, is a position which no man will controvert; but surely Strato was himself as great a dreamer when he made sensation and intelligence result from a certain plastic or spermatic life in matter, which is itself devoid of sense and consciousness. To use the emphatic language of Cudworth, it is indeed inconceivable “how any one in his senses should admit such a monstrous paradox as this, that every atom of dust has in itself as much wisdom as the greatest politician and most profound philosopher, and yet is neither conscious nor intelligent.” It is likewise to be observed of Strato, that though he attributed a certain kind of life to matter, he by no means allowed of one common life as ru.- ing over the whole material universe. He supposed the several parts of matter to have so many several plastic lives of their own, and appears^[3. Cu<lworth, Intellect. System, ed∙ Mosheim, lib. i. cap. 3. ] to have attributed something to chance in the production and preservation of the mundane system.

In denying the existence of a God, perpetually directing his plastic principle, and in supposing as many of these principles as there are atoms of matter, Strato deviated far from the doctrine of Aristotle. The great founder of the peripatetic school, as well as his apostate disciple, taught that mundane things are not effected by fortuitous mechanism, but by such a nature as acts regularly and artificially for certain ends; yet he never considers this nature as the highest principle, or supreme Numen, but as subordinate to a perfect mind or intellect; and he expressly affirms, that “mind, together with nature, formed or fashioned this universe.” He evidently considers mind as the principal and intelligent agent, and nature as the subservient and executive instrument. Indeed, we are strongly inclined to adopt the opinion of Mosheim, who thinks that by nature Aristotle meant nothing more than that ϑ εgμοτης ψ υχικη, or animal heat, to which he attributes immortality, and of which he expressly says^[4. De Generatione Animalium, lib. üi. c. 11. ] that all things are full. Be this as it may, he always joins together God and nature, and affirms that they do nothing in vain. The same doctrine was taught before him by Plato, who affirms that “nature, together with reason, and according to it, orders all things.” It must not, however, be concealed, that Plato seems to have attributed intelligence to the principle by which he supposed the world to be animated; for Chalcidius, commenting on the Tirnaeus, ^[5. Sect 53. ] thus expresses himself: “Haec est illa rationabilis anima mundi, quae gemina juxta meliorem naturam veneratione tutelam praebet inferioribus, divinis dispositionibus obsequens, providentiam nativis impertiens, aeter-norum similitudine propter cognationem beata.” Apuleius, too, tells us,^[6. De Dogmate Platonis. ] “Illam coelestem animam, fontem animarum omnium, optimam virtutum esse genetricem, subserviri etiam Fabricatori Deo, et praesto esse ad omnia inventa ejus.”

The doctrine of Plato has been adopted by many moderns of greateminence both for genius and for learning. Thecelebrated Berkeley, bishop of Cloyne, after describing Plato’s anima mundi, thus recommends the study of his philosophy:^[7. <S ’ iπ¾ No. 338. ] “If that philosopher himself was not read only, but studied also with care, and made his own interpreter, I believe the prejudice that now lies against him would soon wear off, or be even converted into high esteem, for those exalted notions, and fine hints, that sparkle and shine throughout his writings[7:17:798]; which seem to contain not only the most valuable learning of Athens and Greece, but also a treasure of the most remote traditions and early science of the east.” Cudworth, and the learned author of Ancient Metaphysics, are likewise strenuous advocates for the Aristotelian doctrine of a plastic nature diffused throughout the material world; and a notion very similar occurred to a subsequent writer, who does not appear to have borrowed it either from the Lyceum or the Academy.

This writer is Mr Young, of whose active substance, and its agency in moving bodies, some account has elsewhere been given (see Motion). As a mere unconscious agent, immaterial, and, as he expresses himself, immental, it bears a striking resemblance to the plastic nature or vegetable life of Cudworth. But the author holds it to be not only the principle of motion, but also the basis or substratum of matter itself; in the production of which, by certain motions, it may be said to be more strictly plastic than the hylarchical principle, or vis genitrix, of any other philosopher with whose writings we have any acquaintance. Though this opinion be singular, yet as its author is evidently a man who thinks for himself, unawed by the authority of celebrated names, and as one great part of the utility of such works as ours consists in their serving as indices to science and literature, we shall lay before our readers a short abstract of the reasonings by which Mr Young endeavours to support his hypothesis, and we shall take the liberty of remarking upon those reasonings as we proceed.

The author, after a short introduction, enters upon his work,^[8. An Essay on the Powers and Mechanism of Nature. ] in a chapter entitled Analysis of Matter in general. In that chapter there is little novelty. He treats, as others have done, of primary and secondary qualities, and adheres too closely to the language of Locke, when he says, that “the nature of bodies signifies the aggregate of all those ideas with which they furnish us, and by which they are made known.” To say the best of it, this sentence is inaccurately expressed. An aggregate of ideas may be occasioned by the impulse of bodies on the organs of sense, but the effect of impulse cannot be that which impels. We should not have made this remark, which may perhaps be deemed captious, were we not persuaded that the vague and inaccurate use of terms is the source of those mistakes into which we cannot help thinking that the very ingenious author has sometimes fallen. Having justly observed that we know nothing directly of bodies but their qualities, he proceeds to investigate the nature of solidity.

“Solidity,” he says, “is the quality of body which principally requires our notice. It is that which fills extension, and which resists other solids, occupying the place which it occupies; thus making extension and figure real, and different from mere space and vacuity. If the secondary qualities of bodies, or their powers variously to affect our senses, depend on their primary qualities, it is chiefly on this of solidity; which is therefore the most important of the primary qualities, and that in which the essence of body is by some conceived to consist. This idea of solidity has been judged to be incapable of any analysis; but it appears evident to me,” continues our author, “that the idea of solidity may be resolved into another idea, which is that of the power of resisting within the extension of body. Hence it becomes unnecessary, and even inadmissible, to suppose that solidity in the body is at all a pattern or archetype of our sensation.”

That solidity in the body, and we know nothing of solidity anywhere else, is no pattern of any sensation of ours, is indeed most true, as we have shown at large in another place (see Metaphysics) ; but to reconcile this with what our author asserts immediately afterwards, that “solidity is no more in bodies than colours and flavours are, and that it is equally with them a sensation and an idea,” would be a task to which our ingenuity is by no means equal. He affirms, indeed, that solidity, as it is said to be in bodies, is utterly incomprehensible; that we can perfectly comprehend it as a sensation in ourselves, but that in bodies nothing more is required than a power of active resistance to make upon our senses those impressions from which we infer the reality of primary and secondary qualities. This power of resistance, whether it ought to be called active or passive, we apprehend to be that which all other philosophers have meant by the word solidity ; and though Locke, who uses the words idea and notion indiscriminately, often talks of the idea of solidity, we believe our author to be the first writer who has thought of treating solidity as a sensation in the mind.

Though it is wrong to innovate in language, when writing on subjects which require much attention, we must, however, acknowledge it to be unworthy of inquirers after truth to dispute about the proper or improper use of terms, so long as the meaning of him who employs them can be easily discovered. We shall, therefore, follow our author in his endeavours to ascertain what this power of resistance is which is commonly known by the name of solidity. All power he justly holds to be active; and having, by an argument^[9. “λV e can only conceive of solidity as being a resistance of the parts of any body, to a power which endeavours to separate them, or to bring them nearer together. Now that which resists any power, and prevents its effect, is also a power. By resistance, 1 mean here an active resistance, such as an animal can employ against an animal. If a horse pulls against a load, he draws it along; but if he draws against another horse, he is put to a stand, and his endeavour is defeated. When any endeavour to change the situation of the parts of any solid is in like manner prevented from taking effect, and the parts retain their situation, the situation has plainly been preserved by an active resistance or power, equivalent to that which was fruitlessly exerted on them.” Such is our author’s reasoning to prove that matter is essentially active, and that from this activity results our notion of its solidity; but does he not here confound solidity with hardness, and impenetrability with cohesion? He certainly does; for water is as solid, in the proper sense of the word, as adamant, and the particles of air as the particles of iron. The parts of water are, indeed, separated with ease, and those of adamant with difficulty; but it is not because the latter have more solidity than the former, but because the power of cohesion, whatever it may be, operates upon them with greater force. Solidity is an attribute of a whole; hardness and softness result from the cohesion of parts. We do not at all perceive the propriety of the simile of the horse pulling a load, and afterwards pulling against another horse. Is it because both horses are active that one of them cannot prevail against the other, and because the load is inactive that either of them may drag along a mass of iron of half a ton weight? If so, double or triple the mass, and a very strange phenomenon will be the result; for we shall have an active whole compounded of two or three inactive parts, even .though those parts should not be in contact. ] of which we do not perceive the force, attempted to prove that it is by an inward power, and not by its inertia, that one body prevents another from occupying the same place with itself, he naturally enough infers matter to be essentially active. “But the activity of matter is to be considered in a certain limited sense, and its inertness is to be regarded in another limited sense; so that these are compatible within their respective limits. The activity of body may be considered as belonging to the parts of a compound; its inertia as the inertia formed of those parts. The actions of the parts are everywhere opposed to each other, and equal; and hence results the inactivity of the whole.”

Solidity alone of the primary qualities being positive, and peculiar to bodies, and our author having resolved this into action or power, it follows, by his analysis, that the essence of body is reduced to power likewise. But, as he properly observes, power is an idea of reflection, not acquired by the [7:17:799]senses, but suggested by thought. Hence our knowledge of real existence in body must be such as is suggested to us by our thoughts exercised about our sensations. “We are capable of acting and producing changes in appearances; and this faculty, which we experience to exist in ourselves, we call power. We are conscious of the exertion of our own power; and, therefore, when we see action or change happen without any exertion of ours, we refer this to other powers without us, and necessarily conclude the power to exist where the change begins or the action is exerted. This power, then, referred to bodies, must exist in them, or it can exist nowhere.”

In two chapters, which might easily have been compressed into one not so long as the shortest of them, our author analyses atoms or the primary particles of matter, and strenuously opposes their impenetrability. He allows that there are atoms of matter not divisible by any known force; but as these, however small, must still be conceived as having extension, each of them must be composed of parts held together by the same power which binds together many atoms in the same body. This power, indeed, he acknowledges to operate much more forcibly when it cements the parts of a primary atom, than when it makes many atoms cohere in one mass; but still it operates in the same manner; and as the ideal analysis may be carried on in infinitum, the only possible idea which is suggested by atoms, or the parts of atoms, is the idea of a resisting power. That this power of resistance, which constitutes what is vulgarly called the solidity of bodies, may not be absolutely impenetrable, he attempts to prove, by showing that resistance does in fact take place in cases where impenetrability, and even solidity, are not supposed by any man.

“Let us endeavour,” says he, “to bring together two like poles of a magnet, and we shall experience a resistance to their approximation. Why, then, may not a piece of iron, which between our fingers resists their coming together, resist by an efficacy perfectly similar, though more strongly exerted? If magnetism were to act upon our bodies as upon iron, we should feel it; or were magnets endowed with sensation, they would fed that which resists their nearer approach. The resisting extension between the two magnets is permeable to all the rays of light, and, reflecting none, is therefore unseen; but it is easy to conceive that the same power which resists the approach of the iron might resist and reflect some rays of light. We should then have a visible object interposed between the two magnets, as we have before supposed it might be a tangible one. It is likewise easy to conceive that which is tangible and visible so applied to our organs of tasting, of smelling, and of hearing, as to excite ideas of flavours, odours, and sounds. Thus we see that an action, in which no supposition of solidity or impenetrability is involved, may be conceived to assume all the qualities of matter, by only supposing a familiar effect extended in its operation.”

This reasoning is exceedingly ingenious, though perhaps not original; but, what is of more importance, it does not approach so near to demonstration as the author seems to imagine. If magnets operate by means of a fluid issuing from them (see Magnetism), those who hold the solidity or impenetrability of matter will maintain, that each atom of the magnetic fluid is solid and impenetrable. That we do not see nor feel these atoms, will be considered as no argument that they do not exist; for we do not see, nor in a close room feel, the atoms of the surrounding atmo-. sphere; which yet Mr Young will acknowledge to have a real existence, and to be capable of operating upon our senses of hearing and smelling. Let us, however, suppose that by this reasoning he has established the non-existence of everything in the primary atoms of matter except active powers of resistance, and let us see how he conceives the -actions of these powers to constitute what gives us the notion of inert and solid body; for that we have such a notion cannot be denied.

To act he allows to be an attribute, and justly observes, that we cannot conceive an attribute to exist without a substance. “But,” says he, “we have traced all phenomena to action as to a generic idea, comprehending under it all forms of matter and motion as species of that genus. By this analysis, that complex idea we have usually denominated matter, and considered as the substance or substratum to which motion appertained as an attribute, is found to change its character, and to be itself an attribute of a substance essentially active, of which one modification of motion produces matter and another generates motion.” The action of this substance Mr Young determines to be motion; and he proceeds to inquire by what kind of motion it produces matter, or inert and resisting atoms.

“Whatever portion of the active substance is given to form an atom, the following things are necessary to be united in such portion of active substance. First, It must in some respect continually move; for otherwise it would lose its nature, and cease to be active. Secondly, It must also in some other respect be at rest, for otherwise it could not form an inactive atom. Thirdly, It must preserve unity within itself.” The author’s proof of the first of these positions we have given elsewhere; the second he holds to be self-evident; and the third he thinks established by the following reasoning. “Solidity is the result of those actions among the parts of any whole, whereby the unity of the whole is preserved within itself. Several uncohering things may be united by an external bond; this does not constitute these one solid; it may be one bundle; but if several things cohere, and have an unity preserved within themselves, they become one solid. An atom is the least and most simple solid.” ∙ . ∙ ∙

Having thus proved the necessity of these three requisites to the formation of an atom, he observes that “the two first can only be united in a rotation of the portion of active substance about a centre or axis at rest. By such a motion, all the parts successively occupy different places in the orbit of rotation, and therefore move; the centre round which they revolve being at rest, the whole portion is also at rest; and thus the portion is at once moving and quiescent, as is required. The same kind of motion will also fulfil the terms of the third requisite; for a substance having a revolving motion around its own centre, preserves its unity by reason of all the parts preserving the same relation to the centre; and further, a motion of the active substance about a centre or axis will be an activity in the same orbit, which will act upon and resist whatever shall interfere to oppose its activity, or destroy the unity of the sphere, by diverting the course of the revolving motions. The activity or motion of a portion of active substance about a centre will, therefore, give solidity to such portion; for it will give it unity and resistance, and in a manner tie together all the parts, forming them into one mass about their common centre; for they move or are active, not towards the centre, in which case they would be lost in non-extension; nor from the centre, where they would dissipate in boundless space; but about the centre, preserving the same limits of extension. And being in this way active, they in this way resist any other activity opposed to them, that is, they resist any action which tends to penetrate or divide this sphere of revolving activity. Therefore, since any portion of active substance does, by revolving about a centre, become an united, resisting, and quiescent whole, the smallest portions of the active substance which have such motions will become atoms, or make the smallest portions of matter.” [7:17:800]Having thus shown to his own satisfaction how atoms of matter are formed, he next explains, what at first he confesses may appear to be a paradox, “how the active substance, retaining its own nature and essential properties, continuing immaterial, unsolid, and active, puts on at the same time the form of matter, and becomes material, solid, and inert. A sphere of revolving active substance, as it revolves constantly about a centre, and as parts of the substance are considered as successively passing through every point in the orbit; considered thus in its parts, and in its motions, it is active substance, immaterial, and unsolid; but the whole sphere, considered unitically, collectively, and as quiescent, is in this point of view a solid atom, material and inert.”

Such is the active substance of Mr Young, and such his theory of the formation of matter. That he has not with servility copied from the ancients, every reader of his book, who is not an absolute stranger to Greek and Roman literature, will readily acknowledge; and yet, if his theory be well founded, he has discovered a middle substance between mind and matter, more properly plastic than Aris-, totle or Plato, Cudworth or Berkeley, ever conceived. But truth compels us to add, that to us his theory appears to labour under insuperable objections. That there may be in the universe a substance essentially active, and at the same time not intelligent, is a proposition which we are by no means inclined to controvert. Various phenomena, both in vegetable and in animal life, lead us to suspect that there is such a substance; but it does not follow that we are inclined to adopt our author’s doctrine respecting the formation of matter. He conceives his proof indeed to be “in its nature not at all imperfect, or to fall short of demonstration; and if any one refuse it, he thinks it will be necessary for him to show, either that the explanation offered is not sufficient, or that some other explanation will serve equally well.”

To show that the explanation which this writer has offered is not sufficient, will not, we apprehend, be a very arduous task; but we have ourselves no inclination to attempt another explanation, because we believe that of the formation of matter no other account can be given than that which resolves it into the fiat of the Creator. That it cannot be formed by the motion of an immaterial substance, in the manner which our author has very clearly described, seems to be a truth so evident as not to admit of proof; for if motion, as he defines it, be a change of place, everything that is moved must have the quality of extension. But all the parts of this active substance which are given to form an atom, move round a centre, and are expressly said to occupy successively different places in the orbit of rotation. Every one of these parts, therefore, is an extended being: And since, according to our author, solidity is nothing but an active power of resistance, and the parts of this active substance, in their rotation round their centre, act upon and resist whatever interferes to oppose their activity, it follows that each of these parts is likewise a solid being. But, in the opinion of Mr Young himself, and of all mankind, whatever is extended and solid is material. This theory, therefore, exhibits a process in which atoms are formed of a substance which, though it is said to be active, immaterial, and unsolid, appears, when narrowly inspected, to be nothing else than a collection of those very atoms of which the author pretends to explain the formation. Mr Young, who examines and very freely censures some of the doctrines of Newton and others, can scarcely have expected that others would refrain from stating objections to a theory which is quite new, to a transformation which he himself acknowledges may to many “appear not only problematical and difficult to conceive, but wholly impossible, and implying contradictions absolutely and for ever irreconcileable.” Whether this be a just character of it our readers must determine; but if we had not believed the author to be a man of ingenuity, we should not have introduced him or his work to the notice of the public.