The Twenty four Thomistic Theses
Newly translated and annotated by
W. H. Marshner
Decree of the Sacred Congregation for Studies
July 27, 1914
1. Act and potency divide the set of beings in such a way that anything which “is” has to be either (1) pure act or else (2) a combination of potency and act, having these as the primordial factors within it.
2. Since anything’s “act” is a completion it has, act is limited only by a potency which is the thing’s capacity for being completed. Hence, in any order of being where there is a “pure act,” the pure act is unlimited and unique; but wherever an act is limited and has more than one instance, it is occurring in a genuine composition with potency.
3. Therefore, since God in Himself is a pure act of existing, God is unique and subsists as an utterly uncomposed “one.” Since everything else has just a share in the act of existing, everything else has a nature by which its act of existing is restricted. Thus everything else consists of “essence” and “existence” as really distinct factors.
4. A “being” is what a thing is called from its act of being. But “is a being” is not a description applied univocally to God and to creatures; neither is it applied just equivocally; rather, it is applied analogously, by both analogy of attribution and analogy of proportionality.
5. Moreover, there is in every creature a real composition of its subsisting subject [i.e. its sub-stance] with forms added secondarily, i.e. “accidents”; this composition would be unintelligible, unless the creature’s act of being were really received in an essence distinct from it.
6. Besides absolute [non-relational] accidents, there are also relational ones, i.e. accidents of having a bearing towards something. Although the distinctive definition of ‘bearing towards something’ does not say that anything “inheres,” it is often the case that [inherence is involved because] the bearing-towards has its cause in the real, with the result that the “bearing towards” has a real being-status [entitas] distinct from that of the subject in which it inheres.
7. A spiritual creature is entirely simple in its essence. But there are still two levels of composition in it: that of its essence with its existence, and that of its substance with its accidents.
8. A bodily creature, however, is already composed (of potency and act) in its very essence. Its potency and act in the line of essence are called its “matter” and “form.”
9. Neither of these parts has an act of being directly on its own [per se]; nor is either “produced” or “destroyed” directly on its own [per se]; and neither is put into a category except “reductively” as a factor of a substance.
10. Although “being extended” into component parts is a consequence of having a bodily nature, a body’s being a substance is not the same thing as its being so-big. In its own defining make-up, a “sub-stance” is indivisible, not after the fashion of a point, but after the fashion of what is outside the series of dimensions. Being “so big,” however (which gives a substance its extendedness) is really different from the substance and is an “accident” in the proper sense of the word. 
11. By having a definite [signate] size, matter is the source of individuation, i.e. of numerical distinction between one individual and another in the same specific nature, which can have no place among pure spirits.
12. The same accident of size results in a body’s being in a place “circumscriptively;” and in this fashion a body cannot be in more than one place at a time by any power [even God’s power].
13. Bodies are divided into two kinds: some are living, and some are lifeless. In living bodies there needs to be a part inducing change and a part undergoing it, in the same subject. Thus a living body’s substantial form (called its “soul”) requires the body to have an organic arrangement, i.e. to have heterogeneous parts.
14. The souls of vegetative and sense-endowed things never subsist on their own [per se] and are never produced on their own, but only as a factor whereby a living thing exists and lives; and since such souls depend wholly upon matter, if a body-soul composite is destroyed, such a soul is thereby destroyed also as a side-effect [per accidens].
15. By contrast, a human soul does subsist on its own and is created by God when it can be infused into a subject suitably disposed; also, by its own nature, it is indestructible and immortal.
16. This same rational soul is united to a body in such a way as to be its one and only substantial form. By it, a human being has what it takes to be a human and an animal and alive and a body and a substance and a being. Thus a human being’s soul gives him or her every level of completeness as to essence. On top of all that, a human soul communicates to the body the act of existing whereby it itself [the soul] exists.
17. Two series of faculties [i.e., powers, abilities] emerge from the human soul as natural results of it: organ-based ones and ones that are not organ-based. The former, among which are our senses, reside in the body-soul composite; the latter reside in the soul alone. Thus the faculty which is one’s “intellect” is intrinsically independent of a bodily organ.
18. Intellectuality follows necessarily from immateriality and does so in such a way that the more removed a thing is from matter, the higher its level of intellectuality. The object co-extensive with “thing understood” is “a being” in the general sense of ‘a being’; the object distinctive to the human intellect in its present state of union with the body is limited to quiddities abstracted from material conditions.
19. We get knowledge, then, from things available to the senses. But since being sensed is not the same as being actually understood, something else has to be admitted in the soul besides the intellect that is formally said to “do the understanding,” namely, an active power which abstracts intelligible kinds from their sensible appearances.
20. Through these intelligible kinds, we get direct knowledge of “universals”; we get knowledge of particulars (a) by sensation and (b) by the intellect as it turns back to things’ appearances [phantasmata]; but we rise to a knowledge of spiritual things by [using] analogy.
21. Willing comes after understanding, not ahead of it. Our will is determined to seek what is presented to it as such “complete good” as to exhaust our yearning. But our will chooses freely among the many goods presented to it as worthwhile [good in some way]. Each of these is presented to the will by a reversible [practical] judgment. Thus one’s choice follows upon one’s final practical judgment, but one’s will is what makes it the final one.
22. We do not “perceive” that God exists by an immediate intuition, nor do we prove His existence a priori; we prove it, rather, a posteriori by the things that have been made, following an argument from effects back to their cause. E.g., we follow
–– an argument from changing things unable to provide the whole explanation of their changing, to a first and unchanging agent of change;
–– an argument from how things here below emerge from caused causes, to a first and uncaused cause;
–– an argument from destructible things that can just as well not be as be, to a being that absolutely has to be;
–– an argument from things at lesser levels of completeness in how they exist, live, and understand, to a thing which is maximally living, maximally intelligent, and maximally existing; and finally
–– an argument from the order in the universe, to a separate intelligence which puts things in order, disposes them, and directs them to their purpose.
23. Because of the fact that the divine essence, by being actual in exercised act, is identical with Existence itself subsisting, it is well presented to us as it is constituted in its metaphysical character, so to speak; hence its character shows us that it is complete [perfect] in infinitely many ways.
24. By this very purity of His being, God is set apart from all finite things. Hence one infers (1) that the world could only have arisen from creation by God; (2) that the creative power to make a being existent cannot be communicated to any finite nature, even by a miracle, and finally (3) that no created agent has any effect on existence except by a motion received from the first Cause.
- The noun ens means either “a being” or the whole set of them. A being is “a thing which is,” hence a thing which is “in being” and hence in that set. Without qualifiers, “a being” is a thing which exists. Given a qualifier, a being is “a thing which is such-and-such.” ↑
- A thing’s “act” need not be an action it does. It can be the thing’s operative status or its current “actual” state. ↑
- For the verb ‘subsists’, see footnote 6 below. ↑
- Factors are “really” distinct when they are not just “conceptually” distinct (so as to be named or described differently) but are “thing-wise” distinct, i.e. distinct as one thing from another. The adverb ‘realiter’ comes from the noun ‘res’, which means a “thing.” In scholastic Latin, not every “thing” was an object (objectum), because an object was so called in relation to a faculty: object of sight, object of thought, object of desire. A “thing” didn’t have to be the object of any such faculty. ↑
- A term is applied to different things “univocally” when its definition is kept constant, as in “strong ox” and “strong man;” a term is applied to them “equivocally” when it is applied under unrelated definitions, as in “fast day” and “fast car;” a term is applied to them “analogously” when it is applied under related definitions, as in “healthy man” and “healthy diet” (analogy of attribution) or when it captures a “proportion,” such as, God’s power : God’s effects :: a creature’s power : the creature’s effects. ↑
- A “subsisting” thing is a concrete whole (not abstract and not a part) having what it takes to exist “on its own.” An accident, by contrast, is not apt to exist on its own, outside the subject in which it inheres. Typically, an accident exists by inhering. The composition of a subject/substance with its accidents enriches the being of the subject without altering its essence; hence it would be unintelligible if the subject’s being and its essence were not really distinct. ↑
- This thesis addresses the important contention that, while some relations are just products of thought (like x is better liked than y), others are real (like x is the father of y). The real relations are thing-like (realis) because they are “there” whether anyone thinks of them or not. ↑
- This thesis points out the deep differences between a genuine “thing which is” and a mere factor “whereby it is.” The latter is not an item of what-there-is but of how-it-is. What is produced, destroyed, and put into one of Aristotle’s ten categories is “what there-is,” not “how it is.” If Aquinas’s metaphysics had been “first order,” he would have included in “what there is” only sub-stances, and their matter and form would have been only the “how they are” of a material substances. But like Aristotle, of course, he included not only substances but also sizes, qualities, relations, etc. Thus in all ten Categories, a Thomist can distinguish what-there-is (in that category) from how-it-is. The later is called a “mode.” Thus a “heat” of 90˚ C. differs in mode from a “boiling” heat. ↑
- This thesis is against Descartes’ identification of being a body with being extended. To be extended is to have component or “integral” parts lying outside one another, and thus to occupy “so much” space or to be “so big.” Well, a bodily substance like a rabbit can be big or small. Thus, what it takes to be a rabbit is “outside the series of dimensions.” ↑
- Signate matter is the source of individuation in a kind because it is “just enough” matter to make one instance of the kind. Thus an atom of chlorine and an atom of sodium is “just enough” matter to make one instance of salt. Thus, too, a single cell with the right DNA is “just enough” matter to make one instance of a virus, or one instance of a horse. ↑
- This thesis is relevant to the Eucharist, wherein Christ’s body is in many tabernacles at once but is not “circum-scriptively” in those many places, because His body’s substance is in the Eucharist without its accident of size or quantity. ↑
- A thing’s quiddity is an answer to the question, “What is it?” Any useful answer goes beyond mere sense-impressions of the thing, so as to be a way of “understanding” it. Thus the “proper object” of human understanding in this life (where our minds are dependent on our senses) is a what-it-is of one or another empirical thing. (‘Quiddity’ is often a synonym of ‘essence’, but this is misleading unless one is working in a science, where the ‘What is it?” question is looking for an answer which is not just a “handle” on the thing but something as close as possible to its real make-up or scientific definition.) ↑
- This “active power” is called the agent intellect. It performs an operation upon the data of the senses, called abstracting. The intellect which is “formally said to understand” is called the passive or possible intellect. It is so called because it “receives” the abstracted kind into itself (as species impressa) and is thereby put “into act” to understand this kind; whereupon it can “do” the act of understanding, in which it expresses this abstracted kind to itself as a concept (species expressa). Thus any case of understanding “what something is” is a case of bringing it under a concept. ↑
- Since the intelligible kind received and expressed is an abstracted kind, the content of a concept is a universal. Hence the understanding of a universal is antecedent to (not the sensation of, but) the understanding of a particular. A spiritual entity, however, provides no sense data, and hence “what it is” admits of no abstraction. If it is not divinely revealed, it can only be conjectured via analogical reasoning from (and with) concepts reached as discussed above. ↑