On the Creation of Magistrates (1.81-1.85)

For if it was necessary to examine the mortal body of the priest that it ought not be imperfect through any misfortune, much more was it necessary to look into his immortal soul, which they say is fashioned in the form of the living God. Now the image of God is the Word, by which all the world was made.

And after enjoining that the priest is to be of pure blood, and sprung from fathers of noble birth, and that he must be perfect in body and soul, laws are enacted also respecting the garments which the priest must wear when he is about to offer the sacred sacrifices and to perform the sacred ceremonies.

And this dress is a linen tunic and a girdle, the latter to cover those parts which must not be displayed in their nakedness near the altar of sacrifice. And the tunic is for the sake of promptness in performing the requisite ministrations; for they are but lightly clad, only in their tunics, when they bring their victims, and the libations, and the other requisite offerings for sacrifice, being apparelled so as to admit of unhesitating celerity.

But the high priest is commanded to wear a similar dress when he goes into the holy of holies to offer incense, because linen is not made of any animal that dies, as woollen garments are. He is also commanded to wear another robe also, having very beautiful embroidery and ornament upon it, so that it may seem to be a copy and representation of the world. And the description of the ornament is a clear proof of this;

for in the first place the whole of the round robe is of hyacinthine colour, a tunic reaching to the feet, being an emblem of the air, since the air also is by nature black, and in a manner may be said to be reaching to the feet, as it is extended from above