It is not in writing only that they have bequeathed to us the Tradition of the Church, but also in certain unwritten examples. In the twenty-seventh book of his work, in thirty chapters addressed to Amphilochios concerning the Holy Spirit, St Basil says, “In the cherished teaching and dogmas of the Church, we hold some things by written documents; others we have received in mystery from the apostolical tradition. Both are of equal value for the soul’s growth. No one will dispute this who has considered even a little the discipline of the Church. For if we neglect unwritten customs, as not having much weight we bury in oblivion the most pertinent facts connected with the Gospel.” These are the great Basil’s words. How do we know the Holy place of Calvary, or the Holy Sepulchre? Does it not rest on a tradition handed down from father to son? It is written that our Lord was crucified on Calvary, and buried in a tomb, which Joseph hewed out of the rock; (Mt. 27:60) but it is unwritten tradition which identifies these spots, and does more things of the same kind. Whence come the three immersions at baptism, praying with face turned towards the east, and the tradition of the Mysteries? Hence St Paul says, “Therefore, brethren, stand fast, and hold the traditions which you have learned either by word, or by our epistle.” (II Thess. 2.15) As, then, so much has been handed down in the Church, and is observed down to the present day, why disparage images?
If you bring forward certain practices, they do not inculpate our worship of images, but the worship of heathens who make them idols. Because heathens do it foolishly, this is no reason for objecting to our pious practice. If the same magicians and sorcerers use supplication, so does the Church with catechumens; the former invoke devils, but the Church calls upon God against devils. Heathens have raised up images to demons, whom they call gods. Now we have raised them to the one Incarnate God, to His servants and friends, who are proof against the diabolical hosts. (Apologia Against Those Who Decry Holy Images Bk. I)