Whether the union of the Word Incarnate took place in the suppositum or hypostasis?

❌ Objection 1 : It would seem that the union of the Word Incarnate did not take place in the suppositum or hypostasis. For Augustine says (Enchiridion xxxv, xxxviii): "Both the Divine and human substance are one Son of God, but they are one thing [aliud] by reason of the Word and another thing [aliud] by reason of the man." And Pope Leo says in his letter to Flavian (Ep. xxviii): "One of these is glorious with miracles, the other succumbs under injuries." But "one" [aliud] and "the other" [aliud] differ in suppositum. Therefore the union of the Word Incarnate did not take place in the suppositum.

❌ Objection 2 : Further, hypostasis is nothing more than a "particular substance," as Boethius says (De Duab. Nat.). But it is plain that in Christ there is another particular substance beyond the hypostasis of the Word, viz. the body and the soul and the resultant of these. Therefore there is another hypostasis in Him besides the hypostasis of the Word.

❌ Objection 3 : Further, the hypostasis of the Word is not included in any genus or species, as is plain from FP, Question [3], Article [5]. But Christ, inasmuch as He is made man, is contained under the species of man; for Dionysius says (Div. Nom. 1): "Within the limits of our nature He came, Who far surpasses the whole order of nature supersubstantially." Now nothing is contained under the human species unless it be a hypostasis of the human species. Therefore in Christ there is another hypostasis besides the hypostasis of the Word of God; and hence the same conclusion follows as above.