Of the word ΕΙ engraven over the gate of Apollo's temple at Delphi (20)

But God, we must say, is, and he is not in any time, but in eternity, which is immovable without time, and free from inclination, in which there is nothing first, or last, or newer; but being one, it has filled its eternal duration with one only now; and that only is which is really according to this, of which it cannot be said, that it either was or shall be, or that it begins or shall end. Thus ought those who worship to salute and invocate this Eternal Being, or else indeed, as some of the ancients have done, with this expression Εἶ ἴν, Thou art one. For the Divinity is not many, as every one of us is made of ten thousand differences in affections, being a confused heap, filled with all diversities. But that which is must be one, as one must have a being. But diversity, which is esteemed to be different from being, goes forth to the generation of that which

is not. Whence both the first of his names agrees rightly with this God, as do also the second and third. For he is called Apollo, as denying plurality and rejecting multitude; and Ieïos, as being only one; and Phoebus was the name given by the ancients to every thing that is pure and chaste; as the Thessalians even to this day, if I am not mistaken, say of their priests, when on vacant days they abstain from the temples and keep themselves retired, that they purify themselves (φοιβονομεῖσθαι). Now that which is one is sincere and pure. For pollution is by the mixture of one thing with another; as Homer, speaking of a piece of ivory dyed red, said it was polluted by the dye, and dyers say of mixed colors that they are corrupted, and call the mixture itself corruption. It is therefore always requisite for that which is incorruptible and pure to be one and unmixed.