John Damascene, An Exact Exposition of the Orthodox Faith IV.5: In reply to those who ask if Christ's subsistence is create or uncreate

The subsistence of God the Word before the Incarnation was simple and uncompound, and incorporeal and uncreate: but after it became flesh, it became also the subsistence of the flesh, and became compounded of divinity which it always possessed, and of flesh which it had assumed: and it bears the properties of the two natures, being made known in two natures: so that the one same subsistence is both uncreate in divinity and create in humanity, visible and invisible. For otherwise we are compelled either to divide the one Christ and speak of two subsistences, or to deny the distinction between the natures and thus introduce change and confusion.