Letter 428: Theodore Studite, Letter 428; Greek heading: Ἀθανασίῳ τέκνῳ.

"How is it," you say, "that the icon [eikon, the painted image] of Christ is not worshipped with adoration [latreia, the worship due to God alone], but rather the Christ who is venerated [proskynesis] in it, when the veneration is one and the same for both?" Because in the case of Christ himself the veneration is indeed adoring; for in venerating him I venerate together with him the Father and the Holy Spirit alike, which is our Trinitarian veneration and adoration. But in the case of the icon the veneration is the same (for how could it not be? since of those of whom there is one power and one glory, of these clearly there is one reverence and one veneration), yet relative, that is to say, homonymous; for in venerating the icon I did not venerate it together with the others, but I venerated Christ, who is not divided in respect of hypostasis [hypostasis, the individual person], but differentiated in respect of the principle of essence. This veneration is relative, but not adoring, even though it is the same: there [in the case of Christ himself] it is so understood and so called, inasmuch as it is Trinitarian, that is, natural; whereas here [in the case of the icon] it is the reverse, inasmuch as it is relative, that is, hypostatic. For if you were to say "adoring," you would signify that the Father and the Spirit were made flesh just as the Son was, which is absurd. Therefore in venerating the icon of Christ I do not venerate the Godhead, as some assert (for that is what signifies the Trinity; and the Trinity has not been made flesh, far from it); but what then? Christ himself, relatively; for he alone is the God the Word who was made flesh. And in venerating Christ himself it is clear that I have venerated together with him the Father and the Spirit alike. So that in the case of the icon it would rightly be understood and called relative, but in the case of Christ himself adoring, inasmuch as the Father and the Spirit are conceived together with him and venerated together with him.