Brandon L. Wanless AMU Dissertation Section Draft De substantiis separatis 1 (post June 1271) 2 In his later treatise on separated substances—to be distinguished from his earlier disputed questions on spiritual creatures—Aquinas again treats explicitly the categories of genus and species. His treatment here is useful for the present purposes because here in his later career Aquinas again offers the reader a metaphysical account of these categories such that they can serve as a reference point in evaluating their propensity to be applied to the unity of the divine essence. In the De Substantiis Separatis, Aquinas reaffirms that God does not simply possess esse univocally in the same way as creatures or even that he is a being categorically similar to creatures, but that “the First Principle which we call God is most a being [maxime ens].” 3 Moreover, “there can be only one being which is ‘to be’ itself [ipsum esse]” 4 such that “the substance of God is His very act of being,” 5 while all other beings (i.e., every creature) share in being (esse) by way of participation. 6 This participation of being distinguishes the purely spiritual angels from the one pure Spirit who is God and even the angels among themselves as they participate more or less perfectly in being. Creatures participate in esse more or less perfectly precisely according to “a certain determinate mode of being which belongs to this given genus or this given species.” 7 Every composite being considered according to its essence participates in its individual esse through its form—either as subsistent or in composition with matter. 8 For material beings, this is clear on account of the relationship of act and potency which characterize form and matter, respectively. For separated substances, however, their essence relates to their existence as potency to act such that the existence makes actual the essence but is also limited by the same essence. Each specific essence of the angels is a greater or lesser potency for esse. The categories of genus and species, then, are only able to describe composite beings limited in their participation in being. At the same time, however, genus and species serve as unifying categories on account of their determination. Aquinas asserts: “Things which are diverse in number are one in species because the nature of the species considered in itself is one.” 9 This unity of species found among numerically diverse beings is found in its unity of determination from the genus. “Now in this way alone is a species one without qualification, namely, insofar as that which is man is truly 1 Saint Thomas Aquinas, Treatise on Separate Substances: A Latin-English Edition of a Newly-Established Text Based on 12 Mediaeval Manuscripts, trans. and ed. Francis J. Lescoe (West Hartford, CT: St. Joseph College, 1963). Hereafter: De substantiis separatis. 2 Torrell, Saint Thomas Aquinas, Vol. 1, p. 350: “According to the ancient catalogues, this treatise was addressed to Reginald and is later than the first half of 1271, without our being able to say whether it was written in Paris or in Naples.” Cf. pp. 220-221, 435. See also Francis J. Lescoe, “Introduction,” in Treatise on Separate Substances, pp. 3- 6. 3 De substantiis separatis IX, 49. “Primum autem principium quod Deum dicimus, est maxime ens.” 4 De substantiis separatis VIII, 42. “Nihil enim per se subsistens, quod sit ipsum esse, potest inveniri nisi unum solum…” 5 De substantiis separatis XIII, 70. “Dei substantia est ipsum ejus esse.” 6 See De substantiis separatis IX, 48: “For, since it is necessary that the First Principle be most simple, this must of necessity be said to be not as participating in ‘to be’ but as itself being ‘to be’. But because subsistent ‘to be’ can be only one, then necessarily all other things under it must be as participating in ‘to be’.” “Cum enim necesse sit primum principium simplicissimum esse, necesse est quod non hoc modo esse ponatur quasi esse participans, sed quasi ipsum esse existens. Quia vero esse subsistens non potest esse nisi unum, necesse est omnia alia quae sub ipso sunt, sic esse quasi esse participantia.” 7 De substantiis separatis VIII, 43. “…sed particulariter secundum quemdam determinatum essendi modum qui convenit vel huic generi vel huic speciei.” 8 See De substantiis separatis VIII, 44. 9 De substantiis separatis VIII, 42. “Ea quae sunt diversa numero sunt unum specie, quia natura specie secundum se considerate est una.”