We do not adore as gods the figures and images of the saints. For if it was the mere wood of the image that we adored as God, we should likewise adore all wood, and not, as often happens, when the form grows faint, throw the image into the fire. And again, as long as the wood remains in the form of a cross, I adore it on account of Christ who was crucified upon it. When it falls to pieces, I throw them into the fire. Just as the man who receives the sealed orders of the king and embraces the seal, looks upon the dust and paper and wax as honourable in their reference to the king’s service, so we Christians, in worshipping the Cross, do not worship the wood for itself, but seeing in it the impress and seal and figure of Christ Himself, crucified through it and on it, we fall down and adore.
Translated by Mary H. Allies. Edition opa.patristics.john-of-damascus.on-holy-images.en.