ginal sense given above. Aristotle dolines the "ma- terial cause' olovo xo^k^s "" d^Sp'orros ita! 6 ipyvfios T^t (/>iaX^s. That the form of the statue is realized in the bronze, that the lironze is the subjeet of the form, is sensibly evident. These two elements of the statue or bowl are the inlrinsie "causes" of its lieing what it is. With the addition of the efficient and final cause (and of privation) they constitute the whole doctrine of its aetiology, and are invoked as a suHicient expla- nation of "accidental" change. There is no difTiculty in understanding such a doctrine. The determinable " matter" (here, in scholastic terminology, more prop- erly substance) is the concrete reality — brass or white metal — susceptible of determination to a particular mode of being. The determinant is the artificial shape or form actually visible. The "matter" re- mains substantially the" same before, throughout, and after its fashioning.
(2) Primordial Matter. — The explanation is not so obvious when it is extended to cover substantial change. It is indeed true that already, in speaking ot the " matter " of accidental change (substance), we go Ijeyond the experience given in sense perception. But, when we attempt to deal with the elements of cor- poreal substance, we proceed still farther in the pro- cess of abstraction. It is impossilile to represent to ourselves either primordial matter or substantial form. Any attempt to do so incvital)ly results in a play of imagination that tends to falsify their nature, for they are not imaginable. The proper objects of our under- standing are the essences of those bodies with which we are surrounded (of. S. Thomas, "De Principio In- dividuationis"). We have, however, no intuitive knowledge of these, nor of their principles. We may reason about them, indeed, and must so reason if we ■wish to explain the possibility of change; but to im- agine is to court the danger of arriving at entirely false conclusions. Hence whatever may be asserted with regard to primordial matter must necessarily be the result of pure and abstract reasoning upon the con- crete data furnished by sense. It is an inexisting principle invoked to account for substantial altera- tion. But, as St. Thomas Aquinas remarks, whatever knowledge of it we may accjuire is reached only by its analogy to "form" (ibid.). The two are the insepa- rable constituents of corporeal beings. The teaching of Aquinas may be briefly set out here as embodying that also of Aristotle, with which it is in the main identical. It is the teaching commonly received in the School; though various other opinions, to which allusion will be made later, are to be found advanced both before and after its formulation by Aquinas.
(.3) Tlie Xature of Primordial Matter.— For St. Thomas primordial matter is the common ground of substantial change, the element of indetermination in corporeal beings. It is a pure potentiality, or deter- minability, void of substantiality, of quality, of quan- tity, and of all the other accidents that determine sen- sible being. It is not created, neither is it creatable, but rather concreatable and concreated with Form, (q. v.), to which it is opposed as a correlate, as one of the essential "intrinsic constituents" (De Principiis Natura;) of those corporeal beings in whose existence the act of creation terminates. Similarly it is not gen- erated, neither docs it corrupt in substantial change, since all generation and corruption is a transition in which one substance becomes another, and conse- quently can only take place in changes of composite subjects. It is produced out of nothing and can only cease to be by falling back into nothingness (De Na- tura Materise, i). Its potentiality is not a property superadded to its essence, for it is a potentiality to- wards substantial being (In I Phys., Lect. 14). A stronger statement is to be found in " QQ. Disp.", Ill, Q. iv., a. 2 ad 4: "The relation of primordial matter ... to passive potentiality is as that of God ... to active (potentiam activam). Therefore matter is its
passivity as Goil is His activity ". It is clear through- out that St. Thomas has here in view primordial mat- ter in the iittrrino.st defiree of abstraction. Indeed, he isexpli<-it upon tlic point. "That is conunonly called primonlial matter which is in the category of sub- stance as a jiotentiality cognized n/xirl from all sjjecies and form, and even from privation; yet susce])tive of forms and privations" (De spiritual, creat., Q. i,a. 1).
If we were "obliged to define its essence, it would have for specific ditterence its relation to form, and for genus its substantiality" (Quod., IX, a. 6. '.i). Anil again: "It has its being by reason of that which comes to it, since in itself it has incomplete, or rather no being at all" (De Princip. Naturae). Such informa- tion is mainly negative in character, and the phrases eniiployed by St. Thomas show that there is a certain difficulty in expressing exactly the nature of the prin- ciple under consideration. This difficulty evidently arises from the imagination, and with imagination the philosophy of matter hasnothingto do. We must begin with the real, the concrete being. To explain this, and the changes it is capable of undergoing, we must infer the coexistence of matter and form determinable and determinant. We may then strip matter, by abstrac- tion, of this or that determination; we may consider it apart from all its determinations. But once attempt to consider it apart from that analog}' by which alone we can know it, once strip it mentally of its determina- bility by form, and nothing — absolute nothing — re- mains. For matter is neither realizable nor think- able without its correlative. The proper object of intelligence, and hkewise the subject of being, is E71S, Verurn . Hence St. Thomas teaches further that prim- ordial matter is " a substantial reahty " (i. e., a reality reductively belonging to the category of substance), " potential towards all forms, and, under the action of a fit and proportioned efficient cause, determinable to any species of corporeal substance" (In VII Met., sect. 2) ; and, again: "It is never stripped of form and privation; now it is under one form now under an- other. Of itself it can never exist" (De Princip. Natur.). Wliat has been said may appear to deny to matter the reality that is predicated of it. This is not the case. As the determinable element in corporeal substance it must have a reality that is not that of the determining form. The mind by abstraction may consider it as potential to any form, but can never overstep the limit of its potentiality as inexistent (cf. Aristotle's Ti ^I'uirdpxo^'os (Phys., iii, 194b, 16) and real- ized in bodies without finding itself contemplating ab- solute nothingness. Of itself matter can never exist, and consequently of itself it can never be thought.
(4) Privation. — The use of the term "privation" by Aquinas brings us to an exceedingly interesting con- sideration. While primordial matter, as "under- stood" without any form or privation, is an indifTerent potentiality towards information by any corporeal form, the same matter, considered as realized by a given form, and actually existing, does not connote this indefinite capacity of information. There is, in fact, a certain rhythmic evolution of forms observable in nature. By electrolysis only oxygen and hydrogen can be obtained from water; from oxygen and hydro- gen in definite proportions only water is generated. This fact St. Thomas expresses in the physical terms of his time: " If any particular matter, e. g. fire or air, were despoiled of its form, it is manifest that the po- tentiality towards other educible forms remaining in it would not be so ample, as is the case in regard to mat- ter (considered) universally" (De Nat. Mat., v). _ The consideration gives us the signification of ' ' privation ", as used in the theory of substantial change. Matter is "deprived" of the form or forms towards which alone it is potential when actually existing in some one or other state of determination. Hence the distinction that is found in the Opuscule " De Principiis Natura;".
(.5) Permanent Matter. — "Matter that does not con-