Thomas Aquinas is often thought to present a compositionalist model of the incarnation, according to which Christ is a composite of a divine nature and a human nature, understood as concrete particulars. But he sometimes seems to hedge away from this model when insisting on the unity of Christ. I argue that if we interpret some of his texts on the assumption of straightforward compositionalism, we can construct a defence of Christ’s unity within that context. This defence involves the claim (...) that the divine unity is so great, and the relation between Christ’s two natures so unusual, that the divine unity can be transferred to the composite Christ as a “borrowed property”. (shrink)