The claim that article four of Thomas Aquinas’s De unione verbi incarnati is a reversal of his consistently held single esse position is challenged in this paper. The article argues that reading all five articles of the De unione as a single-structured argument discloses a single esse understanding of the Incarnate Word. The very nature of the radically hypostatic union between God and man in Christ is at stake in this dispute. According to Thomas, positing a second esse in Christ not only contradicts the tradition, especially of the Christian East, that he appropriates, but it would also compromise the reality of the hypostatic union itself.
