Gregory of Nyssa, refuting Apolinarius’ Apodeixis:
When the shepherd takes this sheep upon himself, he becomes one with it and speaks with the voice of the sheep to his flocks. How could our human weakness be adequate to comprehend an address by the divine voice? He speaks to us in a human way, that is, as one might put it, in a “sheep-like” way, saying, “My sheep hear my voice.” So the shepherd who has taken the sheep upon himself and speaks to us through it is both sheep and shepherd. He is the sheep in that he has been taken up and a shepherd in that it is he who has done the taking up. Because it is necessary for the good shepherd to give his life for his sheep, so that by his own death he may destroy death, the author of our salvation becomes, in his human nature, both priest and lamb; he is able to share in suffering, and so is able to incur death.