ARTICLE I

OF THE PERSONS AS COMPARED TO THE ESSENCE, SUBSISTENCE AND HYPOSTASIS

Sum. Th. I, Q. xxix, A. 2

WE are inquiring about the divine Persons, and the first point of inquiry is about the Persons in comparison with the essence, subsistence and hypostasis: and it would seem that they are absolutely the same.

             1. Augustine (De Trin. vii, 3) says that the Greeks mean the same when they acknowledge three hypostases in God, as the Latins when they acknowledge three Persons. Wherefore hypostasis and Person signify the same.

             2. But it will be replied that the person differs from the hypostasis in that the latter signifies an individual of any nature in the genus of substance, whereas a person denotes an individual of none but a rational nature.

             On the contrary, Boethius says (De Duab. Nat.) that the Greeks employ the term hypostasis to denote only an individual of rational nature. If, then, person signifies an individual of rational nature, hypostasis and person are absolutely the same.

             3. Names are taken from our idea of the things they signify. Now individuality conveys the same idea in things of a rational nature as in other substances. Therefore an individual of rational nature should not have a special name rather than other individuals in the genus of substance, as though there were a difference between hypostasis and person.

             4. Subsistence is taken from subsisting. Now nothing subsists besides individuals in the genus of substance, in which are accidents and 'second substances', namely genus and species (Praedic.). Therefore only individuals in the genus of substance are subsistences. But an individual in the genus of substance is a hypostasis or person. Therefore subsistence is the same as hypostasis and person.

             5. It will be replied that genera and species in the genus of substance subsist, since to subsist belongs to them according to Boethius (loc. cit.).

             On the contrary, to subsist is to exist by oneself. Hence what exists only in another does not subsist. Now genera and species are only in something else: for they are only in 'first substances,' and if these latter be removed, nothing of the former can possibly remain (Praedic. Substantia). Hence to subsist does not belong to genera and species, but only to individuals in the genus of substance: so that we must still conclude that subsistence is the same as hypostasis.

             6. Boethius (Comment. Praedic.) says that {ousia}, i.e. essence, signifies that which is composed of matter and form. Now this must be an individual, since matter is the principle of individuation. Therefore the essence signifies the individual, and thus person, hypostasis, essence and subsistence are the same.

             7. The essence is signified by the definition, since a definition tells us what a thing is. Now the definition of a natural thing that is composed of matter and form, includes not only the form but also the matter, according to the Philosopher (Metaph. vi). Therefore the essence is something composed of matter and form.

             8. It will be replied that the essence denotes the common nature, while the other three, namely subsistence, hypostasis and person, signify an individual in the genus of substance. On the contrary, universal and particular are to be found in every genus. Now in other genera there are not different names for the particular and the universal; thus quality and quantity are denominated in the same way whether in general or in particular. Neither therefore in the genus of substance should there be different names to denote a universal and a particular substance: wherefore one would think that these terms have the same signification.

             On the contrary, Boethius says (Comment. Praed.) that {ousia}, i.e. essence, signifies that which is composed of matter and form; that {ousiosis}, i.e. subsistence, signifies the form, and hypostasis the matter. Therefore they differ.

             Moreover the same conclusion would seem to follow from the fact that the same author (De Duab. Nat.) explains the difference between these terms.

             I answer that the Philosopher (Metaph. v) says that substance may be taken in two ways. In one sense it is the ultimate subject which is not predicated of another: and this is the individual in the genus of substance: while in another sense it is the form or nature of a subject. The reason for this distinction is that several subjects may have a common nature; thus several men have in common the nature of man. Hence the need of distinguishing that which is one from that which is multiple: for the common nature is signified by the definition which indicates what a thing is: so that this common nature is called the essence or quiddity. Wherefore whatsoever a thing contains pertaining to the common nature is included in the signification of the essence, whereas this cannot be said of all that is contained in the individual substance. For if whatsoever is in the individual substance were to belong to the common nature, there would be no possible distinction between individual substances of the same nature. Now that which is in the individual substance besides the common nature is individual matter (which is the principle of individuation) and consequently individual accidents which determine this same matter. Accordingly the essence is compared to the individual substance as a formal part thereof, for instance, human nature in Socrates. Hence in things composed of matter and form, the essence is not quite the same as the subject, and consequently it is not predicated of the subject: for we do not say that Socrates is his human nature. On the other hand in simple substances there is no difference between essence and subject, seeing that in them there is no individual matter to individualise the common nature, but their very essence is a subsistence. This is clear from what the Philosopher says (Metaph. vii), and from Avicenna, who says (Metaph.) that a simple thing is its own quiddity. Now two things are proper to the substance which is a subject. The first is that it needs no external support but is supported by itself: wherefore it is said to subsist, as existing not in another but in itself. The second is that it is the foundation to accidents by sustaining them, and for this reason it is said to substand. Accordingly substance which is a subject, inasmuch as it subsists, is called {ousiosis} or subsistence, but inasmuch as it substands it is called hypostasis by the Greeks, and 'first substance' by the Latins. It is clear then that hypostasis and substance differ logically but are one in reality. Essence, however, in material substances is not the same as they really, nor yet is it altogether diverse since it is by way of a formal part: but in immaterial substances it is altogether the same in reality while differing logically. Person adds a definite nature to the hypostasis, since it is nothing more than a hypostasis of rational nature.

             Reply to the First Objection. Inasmuch as person adds nothing but the rational nature to the hypostasis, it follows that hypostasis and person are absolutely the same in rational nature; thus seeing that man adds rational to animal, it follows that a rational animal is a man. Hence Augustine's statement is true when he says (De Trin. vii, 4) that Greeks mean the same when they acknowledge three hypostases in God, as the Latins when they acknowledge three Persons.

             Reply to the Second Objection. The word hypostasis in Greek in its proper signification denotes an individual substance of any nature, but through use it has come to mean only an individual of rational nature.

             Reply to the Third Objection. Just as it is proper to an individual substance to exist by itself, so is it proper to it to act by itself. For nothing acts but an actual being: for which reason as heat exists not by itself so neither does it act by itself, but the hot thing heats by its heat. Now to act by themselves is becoming in a higher degree to substances of a rational nature than to others: since rational substances alone have dominion over their actions, so that it is in them to act or not to act, while other substances are acted on rather than act themselves. Hence it was fitting that the individual substance of rational nature should have a special name.

             Reply to the Fourth Objection. Although nothing subsists but the individual substance which is called a hypostasis, it is not said to subsist for the same reason as it is said to substand: it is said to subsist as not existing in another, and to substand inasmuch as other things are in it. Hence if there were a substance that exists by itself without being the subject of an accident, it could be called a subsistence but not a substance.

             Reply to the Fifth Objection. Boethius expresses himself according to the opinion of Plato, who held genera and species to be separate subsistent forms devoid of accidents; and in this view they could be called subsistences but not hypostases. Or we may reply that genera and species are said to subsist, not because they themselves subsist, but because in their natures individuals subsist, apart from all accidents.

             Reply to the Sixth Objection. In material substances essence denotes something composed of matter and form; not indeed of individual but of common matter: thus the definition of man which signifies his essence, includes flesh and bones but not this flesh and these bones. On the other hand individual matter is included in the meaning of hypostasis and subsistence in material things.

             This suffices for the Reply to the Seventh Objection.

             Reply to the Eighth Objection. Accidents are not individualised save by their subjects. Substance alone is individualised by itself and its proper principles; hence it is fitting that only in the genus of substance should the particular have a special name.

             The arguments advanced in a contrary sense may be granted. But it must be noted that Boethius in his commentary on the Categories takes these terms in a different sense from that in which they are usually employed and as he uses them in his work De Duabus Naturis. Thus he applies the term hypostasis to matter as the first substanding principle, whereby the 'first substance' is enabled to underlie accidents: since a simple form cannot be a subject, as he also says (De Trin.). Again he applies the term {ousiosis} to the form as the principle of being: because by it is a thing actual: while he employs {ousia} or essence as indicating the composite. Whence he shows that in material substances both form and matter are essential principles.