Against Julian 3.13.27

Sexual desire’s origin is therefore rightly defined as lying in the fire of life. Once this has been established, bodily desire must be attributed to the one through whom bodily life came into being.

So this appetite is not blameworthy in its general kind, its particular form, or its proper measure, but in its excess. Its kind and form belong to the Creator’s work; its measure to the choice of honorable conduct; its excess to the fault of the will.