Aquinas: A Universe of Individuals

The Philosophical System of Thomas Aquinas, by Maurice de Wulf, edited and adapted for the weby by Jonathan Dolhenty

VIII. A Universe of Individuals

A. The Universe a collection of individual things

Let us imagine for one moment that by some great cosmic cataclysm the activity and movement of the universe were suddenly brought to a stop, and that we were in a position to dissect at our leisure the reality of which the universe is made up, in the same way that archaeologists excavate and study the interior of a house in Pompeii. What would a similar analysis of the world we live in reveal to the mind of a mediaeval schoolman? [1]

We should see in the first place that, in addition to the human race, there are thousands of other beings in existence, and that each one of these is a concrete individual thing, independent of and incommunicable to every other in its inmost nature, recalling the first substance of Aristotle or the monad of Leibnitz. Individuals alone exist. We should find this individuality realized in each plant and animal in the domain of life, and, as for the inorganic world, in the particles of the four elements air, water, fire, earth) or else in a compound resulting from their combination and itself possessing a specific state of being (mixtum). The chemistry of the Middle Ages was very rudimentary, and contained a mixture of truth and falsehood. On the other hand, the metaphysics, although closely bound up with this chemistry, is of an independent development. Indeed, it belongs to the particular sciences to determine what is the primordial particle of corporeal matter in each case. It matters little to the metaphysician whether this turns out to be the molecule or the atom (or even the ion or electron). Le us suppose that it is the atom: then the Schoolmen would say that the atoms of oxygen, chlorine, etc., are the real individuals of the inorganic world, it is to them that existence primarily belongs, and they alone possess internal unity.

What is the nature of these individual realities, which make up the universe?

B. Substance and Accidents

Let us examine more attentively any one of the many things which surround us on all sides, — a particular oak tree, for instance. This particular individual thing possesses many characteristics: it has a definite height, a trunk of cylindrical form and of a definite diameter, its bark is rugged, or ‘gnarled’ as the poets say, its foliage is of a somber color, it occupies a certain place in the forest, its leaves exercise a certain action upon the surrounding air, and itself is in turn influenced by things external to itself by means of the sap and the vitalizing elements which it contains. All these are so many attributes or determinations of being, or, to use the scholastic terminology, so many ‘categories,’ — quantity, quality, action, passion, time, space, relation.

But all the above categories or classes of reality presuppose a still more more fundamental one. Can anyone conceive the being ‘courageous’ without someone who is courageous? Can one conceive quantity, thickness, growth, and the rest, without something — our oak tree in the above instance — to which they belong? Neither the action of growing, nor the extension which comes from quantity, can be conceived as independent of a subject. This fundamental subject Aristotle and the Schoolmen after him call the substance. The substance is reality which is able to exist in and by itself (ens per se stans); it is self-sufficient. It has no need of any other subject in which to inhere, but it is also the support of all the rest, which therefore are called accidents, — id quod accidit alicui rei, that which supervenes on something [2].

Not only is it true that we conceive material realities in terms of substance and accidents, — and no philosophy denies the existence in our minds of these two concepts — but also that substance and accidents exist independently, and outside our minds. In the order of real existence, as in the order of our thought, substance and accidents are relative to each other. If we succeed in proving the external existence of an accident (the thickness of the trunk of the tree, for instance), we thereby demonstrate the existence of the substance (i.e., the tree). If the act of walking is not an illusion, but something real, the same must be equally true of the substantial being who walks, and without whom there would be no act of walking.

Locke and many others have criticized the scholastic theory of substance. Their objections, however, rest on a twofold misconception of what that theory involves. First, it is supposed that one claims to know wherein one substance differs from another. Now scholastic philosophy never pretended to know wherein one substance differed from another in the external world. The concept of substance was arrived at not as the fruit of an intuition, but as the result of a reasoning process, which does not tell us what is specific in each substance, but only that substances are. We know that they must exist, but never what they are. Indeed, the idea of substance is essentially meager in content. We must repeat that we have no right to demand from a theory explanations which it does not profess to give.

A second misconception, that we can easily dispose of, represents the substance of a being as something simply underlying its other attributes. To suppose that we imagine something lying behind or underneath the accidents, as the door underlies the painted color, is simple to give a false interpretation of the scholastic theory, and of course there is no difficulty in exposing this conception to ridicule. But the interpretation is erroneous. Substance and accidents together constitute one and the same concrete existing thing. Indeed, it is the substance that confers individuality upon the particular determinations or accidents. It is the substance of the oak tree which constitutes the foundation and source of its individuality, and thus confers this individuality upon its qualities, its dimensions, and all the series of accidental determinations. This tout ensemble of substance and accidental determinations, taken all together, exists by virtue of one existence, that of the concrete oak tree as a whole. This doctrine will be developed in the next chapter, where we will consider the function of substance in the cycle of cosmic evolution.

No less than the substance of the individual man or oak tree, the series of determinations which affect it deserve our careful attention. Are the figure, roughness, strength, etc., distinct realities existing in one which is more fundamental, and if so in what sense?

To ask this question is tantamount to asking what are these determining or supervening states, which quality a man or an oak tree as rough, strong, occupying space [3]. Let us review the chief classes of accidents, namely quantity, action, quality, space and time, relation.

C. Quantity, action, quality

The substantial object which I call Peter, or any particular lion, does not occupy a mere mathematical point: its body is made up of parts in contact with each other (quantity) and which also exist outside each other (extension). The internal order which is the result of this juxtaposition constitutes the internal or private space or place of the body in question. Extension does not constitute the essence of a material things (as Descartes taught), but it is its primary real attribute or property (proprium), naturally inseparable from it, and the one concerning which our senses give us the most exact information (VI, 2).

At the moment when we imagined a sudden petrification as it were of the universe, all these quantified subjects were engaged in mutual action and reaction. Chemical elements were in processes of combination or disassociation; external objects were giving rise to visual sensations in the eyes of animals and men. For, every substance is active — so much so that its activity forms a measure of its perfection (agere sequitur esse, activity follows upon existence) — and if a being were not endowed with activity, it would a sufficient reason for its existence. The action performed or undergone is a real modification of being, and cannot be denied unless we fly in the face of evidence. It is clear, for instance, that the thought of an Edison enriches the reality of the subject involved. Of course, we do not understand the how, or in what way a being A, independent of B, can nevertheless produce an effect in B. Once again we must not demand from a theory that which it does not pretend to give.

A quality of a being, according to the view of the Schoolmen, modifies it really in some specific character, and allows us to say of what kind it is (qualis). Rigorously speaking, this is not a definition, as the notion is too elementary to be strictly definable. The natural figure or shape, for instance a face or a mouth of a certain type, belongs to the group of qualities (figura). It arises from the disposition or arrangement of quantified parts, but it determines the being otherwise than in its mere extension.

Beside the figure of a being, the Schoolmen introduce a second group of qualities, consisting of the intrinsic powers of action, or capacities, — reservoirs, as it were, from which the action flows — for instance, when we say of a man that he is intelligent or strong-willed. They are known as powers (potentiae) in general, and as ‘faculties’ in the case of man. Thomas maintains that every limited being acts by means of principles of action. Only the Infinite Being acts directly through its substance, because in Him existing and acting are identical.

Finally, experience shows that faculties, by being exercised, acquire a certain real pliability or facility which predisposes them to act more easily or with more energy. The professional competency of an artisan, the muscular agility of a baseball player, the clear-headedness of a mathematician, the moral strength of a temperate or just man, — are all dispositions more or less permanent, lasting ‘habits,’ ‘virtues,’ which vary in different subjects, but all of which enrich the being of the one possessing them, since they collaborate with the power of action regarded as a whole.

D. Space and Time

We can only touch on the question of space, which Aquinas, in common with other Schoolmen, considers at great length — not only the internal space proper to each body and which he identifies with its material enclosure, but space as a whole, the result of the juxtaposition of all existing bodies. This space is obviously a function of the material things which actually exist. The ‘multitude’ of such beings might be without limit, for there is no contradiction in supposing an indefinite multitude of material things each occupying an internal space finite in extent. Space as a whole, therefore, being the sum of these individual spaces, might be indefinite.

In the opinion of Thomas, time is really the same as the continuous movement or change in which all real beings are involved. But there is, by a mere mental activity, a breaking up, a numbering of this continuous movement into distinct parts, which in consequence necessarily appear to be successive. Tempus ets numerus motus secundum prius et posterious [4] is the pregnant definition which Thomas borrows from Aristotle. Time is the measure of the (continuous) change, which the mind views as a succession of parts. The present and fleeting state of a changing being is alone real and existing. In the supposition of a motionless world which we made above, the present time would be a cross section of the universe, in its actual state, viewed in relation to the past and to the future. Now, since the multiplicity of beings is not necessarily limited, we may, by a process similar to our reasoning on space, conclude that time, the measure of changes which have really taken place or will take place in the future, may also be without limit in either direction [5].

E. Relations

Passing over the passive, intransitive state (for instance, the state of being sad) which the Schoolmen regarded as a reality distinct from the subject which it affects, there remains the last of the categories, namely, relation. By means of this, the millions of beings which make up the universe, were, at the moment when we have supposed them to be arrested in their course, all bound up in a close network. By virtue of relations some things are for other things, or stand in a particular way towards other things (ad alterum). For instance, it is in virtue of a relation that several men are greater or smaller than others, stronger or weaker, more virtuous or vicious, jealous of others, well or badly governed, etc. Is the relation ‘greater than’ distinct from the size or quantity of the thing in question, the quantity being obviously the foundation of the relation? Thomas replies in the negative, and he would not have allowed that these relations have a separate reality of their own. My being greater or smaller than some particular Black African is not a new reality added to my figure or to my absolute size; otherwise, while retaining continuously the same figure, I should be constantly acquiring or losing realities, every time that Black Africans increased or diminished their size, which is evidently ridiculous.

Let us continue the investigation of our dead universe. For there are two other static aspects of the ensemble of things: their hierarchical arrangement and multiplicity on the hand, and certain attributes known as the ‘transcendentals’ on the other.

F. Grades of reality and multiplicity in each grade

Although each material thing is itself, it is easy to see that there are many men all belonging to the same kind, in that these individuals possess a substantial perfection which is similar. On the other hand, being ‘man’ and being an ‘oak’ belong to different grades of reality.

The explanation is that every material substance has within itself a specific principle (we shall call it later substantial form), and the specific principle of the oak is altogether different from that of man, that of oxygen from that of hydrogen, and so on. The universe of the Schoolmen is hierarchically arranged or graded, not merely by quantitative differences (mechanistic theory) but according to their internal perfection (dynamism). A consequence of this is that the substantial perfection of man or oak tree does not admit of degrees [6]. One is either a man or one is not: we cannot be things by halves. Essentia (id est substantia) non suscipit plus vel minus. — Essence or substance does not admit of more or less. The substance of man is the same in kind in all men. From this there will follow certain important social consequences which we shall take up later.

On the other hand, we see in one and the same substantial order of reality an indefinite number of distinct individuals. Whether we consider the past or the future, there are millions of oak trees, millions of men. Are individuals belonging to the same species just doubles or copies of each other? Have different men or different oak trees exactly the same value as realities? No. Although their substantial perfections are the same in nature and value, their accidents differ, and especially their qualities, quantity, and actions. Men or oak trees are born with different natural aptitudes, and their powers of action differ in intensity. Even two atoms of hydrogen (supposing the atom to be the chemical unit) occupy different places and have different surroundings, which is sufficient to differentiate them. Equality of substance, and inequality of accidents is the law which governs the distinction of individuals possessing the same grade of being so far as substantial perfections are concerned. We shall see that the existence of men together in society is simply an application of this principle.

G. Internal unity, truth, goodness

Since every being, which really exists or is capable of existing, is itself an individual, it possesses internal unity. Ens et unum convertuntur, — being and unity are mutually convertible terms. Unity is simply an aspect of being. Parts of a thing, whether they are material or otherwise, all coalesce and do not exist for themselves, but for the individual whole. We must be careful here to avoid a wrong interpretation of this doctrine. The unity in question is the unity of the individual being, as found in nature; thus the unity of a man, an animal, a plant, or an atom. The unity of such an individual is quite distinct from that of a natural collection (e.g., a mountain, or a colony in biology), or an artificial one (such as an automobile, or a house). To these we attribute a nominal unity, for they are in themselves a collection of millions of individual things, united, in ways more or less intricate, by means of accidental states. A society of men is a unit of this kind.

Everything can become the object of intelligence, and in this sense, which we have met above (VI, F), everything is true.

Again each being aims at some end by means of its activities, and that end is its own good or perfection. There would be no sufficient reason for a being to act, except for that which is suitable for itself (bonum sibi). Hence good is called “that which all things desire,” bonum est quod omnia appetunt. Each thing is good in itself, and for itself. St. Augustine remarks that this is true even of such things as the scorpion, for its poison is harmful only to other beings. This tendency towards well-being, which is deeply rooted in everything, manifests itself in a way conformable to the specific nature of each being. It is blind and unconscious in the stone which falls, or in a molecule which is governed by its chemical affinities; it is conscious but necessitated or ‘determined,’ as moderns say, in a savage beast in presence of its prey; it may be conscious and in addition it may be free in the case of man.

Unity, truth, goodness, are called ‘transcendental attributes,’ because they are not special to some particular class or category of beings, but are above classes (trans-cendunt) and are found in all and every being.

H. Scholasticism the sworn enemy of Monism

The individuality of a number of beings involves their being distinct: one substance is not the other. Since the universe is a collection of individual things, scholasticism is the sworn enemy of monism, which regards all or several beings as coalescing into one only. For Aquinas, monism involves a contradiction. For, it must either deny the real diversity of the various manifestations or form of the One Being, and in that case we must conclude that multiplicity is not real but an illusion; — or else it must maintain that such diversity is real, and then it follows that the idea of unification or identity is absurd.

In other words, the diversity and mutual irreducibility of individual substances are the only sufficient reason for the diversity manifested in the universe. We shall see later that the analysis of the data of consciousness furnishes a second argument against monism, so far as individual human beings are concerned (X, A).

Although this reasoning can be applied to all forms of monism, Thomas Aquinas combats principally those systems which were current in his day, — the extreme Metaphysical Monism of Avicebron, the Materialistic Monism of David of Dinant, and the Modified Monism or Monopsychism of the Averroists of the West, which maintained that there is only human soul for all mankind.



  1. We pass the scholastic doctrine concerning the constitution of the heavenly bodies, for the sake of brevity.

  2. “An accident need not be accidental in our use of the word, but it must be incidental to some being or substance.” — Wicksteed, Ph.H. The reactions between dogma and philosophy, illustrated from the works of S. Thomas Aquinas. London, 1920, p. 421.

  3. It is clear from the above that substance is not quite the same as essence. Substance has its own essence, and accidents have theirs.

  4. De tempore, cap. 2.

  5. Concrete space and time just discussed are altogether different from ideal space and time, which, by a process of abstraction and universalization, are separated from all relation to our universe and can be applied mentally to an indefinite number of possible worlds.

  6. It is based ultimately upon an unchangeable relation with God, whose perfection it imitates.

The late Dr. Jonathan Dolhenty was the Founder and President of The Center for Applied Philosophy and the Radical Academy, and is Honorary Philosophy Editor at Self-Educated American. Self-Educated American has adopted these projects beginning with a republishing and preserving of all of Dr. Dolhenty’s work.