1 “[D]icendum quod persona sive hypostasis Christi dupliciter considerari potest. Uno modo, secundum id quod est in se. Et sic est omnino simplex: sicut et natura Verbi. Alio modo, secundum rationem personae vel hypostasis, ad quam pertinet subsistere in aliqua natura. Et secundum hoc, persona Christi subsistit in duabus naturis. Unde, licet sit ibi unum subsistens, est tamen ibi alia et alia ratio subsistendi. Et sic dicitur persona composita, inquantum unum duobus subsistit.” Summa theologiae (henceforth ST), ed. Caramello, Petrus (Turin and Rome, 1952–56), III, q. 2, a. 4, resp. Another discussion of Christ's compositeness is found in Scriptum super Sententiis Magistri Petri Lombardi III (henceforth 3S), ed. Moos, Maria Fabianus (Paris, 1933), d. 6, q. 2, a. 3, which approaches the issue differently but is consistent with the text being considered here. In developing the ideas in this paper, I have benefited from conversations with, and written comments from, Cross, Richard, Gorman, Anne-Marie, Lamb, Matthew, Pasnau, Robert, White, Kevin, and Wippel, John.Google Scholar

2 This account of the notions of union in person and union in nature, and how Thomas uses them in Christology, is quite compressed. I explain these matters in detail in my “Uses of the Person-Nature Distinction in Thomas's Christology,” Recherches de théologie et philosophie médiévales 67 (2000): 58–79.CrossRefGoogle Scholar

3 The latter argument is raised as an objection to Thomas's Christology by Hughes, Christopher, On a Complex Theory of a Simple God (Ithaca, N.Y., 1989), 241–51. At 250–51: “[I]n order to hold fast to divine incomposition, Aquinas will have to say that in at least one case, something is a man without (ever) having either a human body, or any of that body's parts, among its parts…. I don't, however, see how a being that never has any human bodily parts… could be a human being….” Google Scholar

4 For a discussion of different senses of suppositum in Thomas's thought, see Schweizer, Othmar, Person und hypostatische Union bei Thomas von Aquin (Freiburg, 1957), 86–89, 117–21.Google Scholar

5 That Christ has a multiplicity of human parts is presupposed in ST III, q. 2, a. 5, on whether Christ's body and soul are united, as well as in many other places.Google Scholar

6 For impassibility, see Summa contra gentiles (henceforth SCG), (Rome, 1934), I.16; ST I, q. 3; ST I–II, q. 22, a. 2, ad 1; for immutability, see ST I, q. 9.Google Scholar

7 For the theory of mixed relations and this application, see ST I, q. 13, a. 7. For some complications, see Henninger, Mark, Relations: Medieval Theories 1250–1325 (Oxford, 1989), 31–39. For Henninger, the most important issue for Thomas in developing the mixed relations theory is divine transcendence, not immutability; as the quotations from Thomas given here show, however, Thomas does use the mixed relations theory, at least in Christology, to handle the problems of impassibility and immutability.Google Scholar

8 “[D]icendum quod unio de qua loquimur est relatio quaedam quae consideratur inter divinam naturam et humanam, secundum quod conveniunt in una persona Filii Dei. Sicut autem in Prima Parte dictum est, omnis relatio quae consideratur inter Deum et creaturam, realiter quidem est in creatura, per cuius mutationem talis relatio innascitur: non autem est realiter in Deo, sed secundum rationem tantum, quia non nascitur secundum mutationem Dei. Sic igitur dicendum est quod haec unio de qua loquimur, non est in Deo realiter, sed secundum rationem tantum: in humana autem natura, quae creatura quaedam est, est realiter” (ST III, q. 2, a. 7, resp.); “Esse autem hominem convenit Deo ratione unionis, quae est relatio quaedam. Et ideo esse hominem predicatur de novo de Deo absque eius mutatione per mutationem humanae naturae, quae assumitur in divinam personam. Et ideo, cum dicitur: Deus factus est homo, non intelligitur aliqua mutatio ex parte Dei, sed solum ex parte humanae naturae” (ST III, q. 16, a. 6, ad 2); see also 3S d. 1, q. 1, a. 1, ad 1; 3S d. 7, q. 2, a. 1, ad 1–3. For a useful discussion of an ambiguity in Thomas's presentation, see Weinandy, Thomas, “Aquinas and the Incarnation as Act: ‘Become’ as a Mixed Relation,” Doctor Communis 32 (1979): 15–31. Weinandy argues that although Thomas will sometimes say that God is only conceptually related to creatures or that the Word is only conceptually related to its humanity, he does not mean that these relations hold only because of some judgment on our part, despite the fact that Thomas explains “conceptual relation” in this way. As Bearsley puts it, although the Word is not “really” related to the humanity, it is “truly” related to it; see Bearsley, P. J., “Jesus the Son of Mary according to St. Thomas Aquinas,” Angelicum 55 (1978): 104–5, 113, 116.Google Scholar

9 Whether one wishes to call such an inter-hypostatic relation a “union” or not depends upon whether one thinks that unions can be inter-hypostatic; see my “Uses of the Person-Nature Distinction,” 71–74. Note that, in any case, if the creator–creature relation were a union in person, there would be no created supposits, which would upset the orders of creation and salvation; see ST III, q. 4, a. 5.Google Scholar

10 “[Q]uamvis Verbum non sit constitutum per naturam humanam ut sit simpliciter, tamen per naturam humanam constituitur quod sit homo” (3S d. 6, q. 1, a. 1, qa. 4, ad 1).Google Scholar

11 “Non enim ex natura humana habet Filius Dei quod sit simpliciter … sed solum quod sit homo” (ST III, q. 3, a. 1, ad 3).Google Scholar

12 Thomas's, disputed question on the incarnation, as found in the Marietti edition, seems to contradict this: “Unde non oportet quod natura [sc. humana] sit simplicior et formalior illo homine qui est Verbum caro factum, et constituens ipsum in quantum est homo.” Quaestio disputata de unione Verbi incarnati (henceforth DU), in Quaestiones Disputatae , vol. 2, ed. Calcaterra, M. and Centi, T. S. (Turin and Rome, 1953), a.1, ad 15. The provisional Leonine text of this passage, however, reads differently: “Unde non oportet quod natura [sc. humana] sit simplicior et formalior Verbo secundum se, sed est simplicior et formalior illo homine qui est Verbum caro factum et constituens ipsum in quantum est homo.” Although the Word in itself is not constituted as human by Christ's human nature, the man who is the Word made flesh is so constituted. I would like to thank Fr. Adriano Oliva, O.P., Propresident of the Leonine Commission, for generously granting me permission to quote this unpublished text.Google Scholar

13 “Mutability” is a somewhat misleading term here; for Thomas, change involves imperfection, which means that the incarnation cannot be a “change,” even though it is a case of “becoming” (cf. ST III, q. 16, a. 6, ad 2; 3S d. 7, q. 2, a. 1, ad 1). Nonetheless, I will continue to speak of “mutability” to avoid overuse of cumbersome expressions such as “ability to become other than one is.” Google Scholar

14 “[H]aec est falsa: Homo Christus esse incoepit; sed haec est vera: Christus incoepit esse homo” (ST III, q. 16, a. 9, ad 3). See also 3S d. 7, q. 2, a. 1, ad 4: “Quamvis enim suppositum illud semper fuerit, non tamen semper fuit suppositum humanae naturae.” Google Scholar

15 “Homo significat habentem humanitatem” (ST III, q. 17, a. 1, resp.).Google Scholar

16 I will speak of Christ's divinity and humanity as his “constituents,” not as his “parts.” For reasons why Thomas would not want to speak of “parts” in this case, see 3S d. 6, q. 2, a. 3, ad 4, and ST III, q. 2, a. 4, obj. 2 and ad 2. For a good discussion of the notions of part and whole in Thomas's Christology, see Bro, Bernard, “La notion métaphysique de tout et son application au problème théologique de l'union hypostatique,” Revue Thomiste 68 (1968): 181–97, 357–80.Google Scholar

17 See ST III, q. 16, aa. 1, 4.Google Scholar

18 It will be noted that here I am using the word “change.” The human modifications that Christ undergoes in his human life are in fact changes in Thomas's sense.Google Scholar

19 Hughes, , On a Complex Theory of a Simple God , 253–64.Google Scholar

20 If someone wants to say, “The Word walks down the street,” this will be true, but it must be understood correctly. For Thomas, the subject term here is to be taken materially, as referring to the whole supposit of Christ, without regard to what formality is at work. See ST III, q. 16, a. 7, ad 4.Google Scholar

21 “Dicendum quod Dominus gloriae dicitur crucifixus, non secundum quod Dominus est gloriae, sed secundum quod erat homo passibilis” (ST III, q. 46, a. 12, ad 1). For the general point about passibility, see ST III, q. 14, a. 1, and q. 16, a. 4. Even more generally, Thomas holds that Christ has accidents through the mediation of his humanity; see 3S d. 6, q. 1, a. 1, qa. 3, ad 3.Google Scholar

22 The discussion in this and the previous section raises the following problem. Thomas wants to reconcile a kind of passibility and mutability with divine impassibility and immutability. Appealing to Christ's compositeness, he holds that Christ is both divine and human and then goes on to claim that Christ qua divine is impassible and immutable and that Christ qua human is passible and mutable. Is he (Thomas) not then committed to the self-contradictory view that Christ is impassible and passible, immutable and mutable? The solution to this problem would depend on, among other things, the answer to the question whether “Christ qua X is Y” implies “Christ is Y.” Investigation of such questions would lead us very far from our present concerns. At present, therefore, all I can say about this problem is that I am not trying to solve it here.Google Scholar

23 “Considerandum est autem, quod aliquae formae sunt quibus est aliquid ens non simpliciter, sed secundum quid; sicut sunt omnes formae accidentales. Aliquae autem formae sunt quibus res subsistens simpliciter habet esse; quia videlicet constituunt esse substantiale rei subsistentis” (DU a. 4, resp.). See also SCG IV, c. 49.Google Scholar

24 “Hoc est etiam quod Philosophus frequenter nominat quod quid erat esse, id est hoc per quod aliquid habet esse quid.” De ente et essentia (henceforth DEE), ed. Leon, . vol. 43, c. 1.Google Scholar

25 Cf. DEE c. 6.Google Scholar

26 Cf. Sentencia Libri De Anima , ed. Leon, . vol. 45/1, Book II, c. 1, lines 258–88.Google Scholar

27 For other texts that support the idea that Christ's humanity performs one function but not the other, see the following: 3S d. 10, q. 6, a. 2, qa. 1, ad 1–2; 3S d. 12, q. 1, a. 1, ad 2; ST III, q. 2, a. 3, ad 3; ST III, q. 16, a. 6, ad 1; ST III, q. 16, a. 12, resp., ad 1.Google Scholar

28 “[N]ec Petrus, inquantum homo, est persona, sed inquantum iste homo” (3S d. 10, q. 1, a. 2, qa. 1, ad 2); see also 3S d. 10, q. 1, a. 2, qa. 2, ad 1; ST III, q. 2, a. 2, ad 2.Google Scholar