modern physics. Possessed with this firm conviction himself and desirous that others, whom it more immediately concerns, should share in a like conviction, he has been induced to go somewhat out of his way, and perhaps to forestall certain subjects of subsequent investigation, in order that the doctrine of the School touching the constitution of bodies, and especially as to their substantial Forms, may be presented to the reader in its full integrity. To this intent the six following Theses have been introduced, in order to elucidate the solution of the problems that follow and are immediately connected with the subject of the present Section.

PROPOSITION CCXI.

All substantial bodily Forms in their own partial entity are simple and unextended.

PROLEGOMENON.

By the term simple is not to be understood such simplicity as is attributable to a mathematical point; but a simplicity by virtue of which the Form is entirely in the whole substantial composite and entirely in each and every actual or possible part. When it is said that all such Forms are in this sense simple, it is intended to include the Forms of inanimate, as well as animate, substances.

I. THE FIRST MEMBER of this Proposition, wherein it is asserted that all substantial Forms in their own partial entity are simple, is thus proved. The substantial act of a pure passive potentiality must be simple. But such is every substantial Form. Therefore, etc. The Major is thus declared. There cannot be more than one substantial act informing one and the same portion of matter; and that act specifically and individually determines the whole. Further: As Form of the matter it constitutes the parts, whatever these may be, and is prior to them in order of nature. Therefore, it is Form of the whole; and, as Form of a simple whole, is wholly its act. This no changes,--or rather, determinations,-can affect; for nothing can limit itself. When, then, parts or organs are constituted in the composite through the actuation of the Form; the Form is wholly in each, because it is wholly the act of the whole matter. Further: If we suppose it to exist only partially in the parts, though wholly in the whole; it must be composite in its own nature and, consequently, its components prior in order of nature to itself. Hence, it could not primarily be the act of matter, but of the parts constituted by itself; which is absurd. For, in such a hypothesis, the sum of its

partial informations would constitute the integral information of the whole; not the integral information of the whole, the information of the parts. Once more: If the substantial Form partially informed the organs and parts of the composite; it would not be one act, but many,-each with its own distinct operation. Thus, for instance, the plant-Form would be no longer one; but there would be the root-Form, the leaf-Form, the tissue-Form, etc., collectively forming one nominal whole. These arguments are confirmed by the testimony of experience. Divide a diamond or a piece of sulphur, if this were possible, into atoms; each atom would be a diamond or sulphur, just as truly and completely as the original mass from which it had been taken.

II. THE SECOND MEMBER, which declares that all substantial bodily Forms in their own partial entity are unextended, is evident; for extension is equivalent to quantity which is an accident of the composite. Hence, all bodily substances, previous to their information by quantity, would be unextended and naturally indivisible; à fortiori their essential constituents.

PROPOSITION CCXII.

All material composites, constituted by a living Form, have parts and organs proportioned to the natural operation and faculties of their respective Forms.

This Proposition virtually contains three Members. In the first it is maintained that, in strictness of speech, parts and organs are predicated of the integral composite, and not of either the matter or the Form separately. In the second it is asserted that all living bodies have parts and organs. In the third it is added that these parts and organs are proportioned to the natural operation and faculties of their respective Forms. Let us consider each by itself.

I. THE FIRST MEMBER, which is to the effect that parts and organs are, strictly speaking, attributable to the composite substance, not to either the matter or the Form separately, is thus proved. Parts and organs connote physical composition. But both matter and the substantial Form are simple entities. Therefore, neither of them separately can have either parts or organs. Consequently, it remains that parts and organs are strictly attributable only to the integral composite, or material substance. Again: Parts and organs are properties of living bodies,-that is to say, accidents flowing from the essence of bodies. But accidents essentially presuppose

the integral substance as their only adequate Subject of inhesion. Therefore, etc.

Nevertheless, parts and organs are attributed to the matter in the composite rather than to the Form; because in its partial entity matter, as a passive potentiality, is receptive of such dispositions, which a Form or act, exclusively as such, is not.

NOTE.

An inanimate substance may have virtual substantial parts, forasmuch as it is a compound. Thus, water is virtually made up of oxygen and hydrogen. Such partibility is plainly enough independent of that virtual divisibility into parts, common to all bodies, which is the result of quantity. The two can be easily distinguished; for the latter only multiplies the substance, while the former resolves it into its constituent elements.

II. THE SECOND MEMBER, in which it is affirmed that all living bodies have parts and organs, is thus proved. It has been already established that the matter in the composite substance must be proportioned to the Form. Consequently, the Form in its actuation of the matter introduces into this latter all those determinations which are necessary in order to establish such proportion. In plants, then, -to assume the lowest grade of life,--there are three faculties, viz. those of assimilation, growth, reproduction. In order, therefore, to enable the typical plant-Form, (for it is not necessary for our present purpose that the differentiations of vegetative life should be considered), to exercise the peculiar functions and operation which belong to its nature, it is necessary that the body should be fitted to both; since its functions and operation are purely material. Thus, to keep to the original illustration,—for its functions of assimilation and growth the plant-Form needs organs; it finds. them in its roots, leaves, veins, tissue. For its function of reproduction it needs organs; it finds them, in the sperm and germ-cells. So then, it must have parts in the composite of which it is the act, because separate organs connote diversity of parts. It must have organs; because organs, (as the Greek derivation sufficiently indicates), are the instruments of function, and through function the plant-Form evolves its natural operation. Without these it would be naturally impossible for the plant-Form to energize in accordance with its own nature; which means, in other words, that the matter would not be duly proportioned to its Form.

III. THE THIRD MEMBER asserts, that these parts and organs are duly proportioned to the natural operation and special faculties of the respective Forms. This proposition follows, as a corollary, from the preceding Member. For if it is necessary for the due apportionment of matter to its Form, that it should be organized in accordance with the natural functions of its Form; it follows that the number aud nature of parts and organs must be proportioned to the number and nature of the functions of the Form. Thus it is,-for instance,--that an animal requires organs of sense; over and above the organs of assimilation, growth, and reproduction, that are required for the natural operation of the plant-Form; and a greater or less number of organs in proportion to the excellence of its Form.

COROLLARY I.

It follows that matter, as existing in the composite,-that is to say, under information of its Form,-is the proper seat of parts and organs, (as has been noticed in the declaration of the first Member); since these are instruments of the Form, by means of which it is enabled to energize. Of itself the Form is simple; and in the composite, as substantial Act, preserves its simplicity. Matter, on the contrary, is susceptive of differentiation. In other words, matter of itself is simple by reason of its entitative imperfection; the Form is simple by virtue of its entitative excellence.

COROLLARY II.

The Form causes distinction of parts and organs proportionably to the perfectness of its formal causality. Consequently, within the limits of the same species, these parts and organs are susceptible of appreciable modification according to the exigencies of the individual Form. Thus,-to take an illustration from botany,the flowers of the snowdrops are, as we know, hermaphrodite. In the instance of double snowdrops, the stamina transform themselves into petals. When this occurs, the ovary pines away; because the function of fertility is arrested by the accidental transformation of the stamina. Similarly, the mole is born with the organ of sight, like other mammalia; but the organ does not grow with the growth of the animal and, in the adult, ceases to function. This latter is an instance of specific modification.

COROLLARY III.

All substantial bodily Forms have certain proper virtues or facul

ties proportioned to their grade. Those of inanimate bodies are comparatively few and simple; but they become more numerous and complex, as we mount higher in the scale of nature. Their correlation is due to the unity of their Form. They are limited in act, such, at least, as do not transcend the sphere of matter,to the part or organ through which they energize. Hence there arises a twofold way of regarding these Forms. We may either consider them as they are in their essential nature,-in their first act;—and, as such, they are simply and wholly in every part of the body. Or we may consider them functionally,—in their second act; —and, as such, they admit of physical distinction and partial localization. Thus, the function of sight is limited to the eye; and that of hearing normally in great measure to the ear.

NOTE.

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Against the truth of the third Member of this Proposition it may possibly be objected, that modern observations in comparative anatomy have discovered certain rudimentary structures in higher orders of animals, more or less' useless to' their organism, valueless for life-purposes, worthless for' their 'functions.' Thus; in man the os coccygis affords the rudimentary structure of a tail; and in the human scapula, or shoulder-blade, there is a process of the bone, called the coracoid process, (because of its resemblance to the beak of a crow), which in the bird is an independent bone, doing duty as a fulcrum for the downward sweep of the wing. But these physical facts offer no real difficulty, if we accept the teaching of Aristotle and of the Angelic Doctor. They are the result of the action on the matter of antecedent provisional Forms that have carried on the organization to its appointed term; and their arrest is due to the action of that higher Form which finally determines the specific nature.

PROPOSITION CCXIII.

No substantial bodily Form is absolutely capable of quantitative totality; although all such Forms are presentially and functionally determined by the quantity of the composite substance either wholly or in part, according to the specific nature of each.

PROLEGOMENON I.

By quantitative totality is to be understood that continuous unity,

1 Ernst Haeckel's Evolution of Man, ch. 5 (vol. i. p. 109, Eng. Trans.). See the instances there given.