9 What, then, shall we say? That gods beget and are begotten? and that therefore they have received organs of generation, that they might be able to raise up offspring, and that, as each new race springs up, a substitution, regularly occurring, should make up for all which had been swept away by the preceding age? If, then, it is so—that is, if the gods above beget other gods, and are subject to these conditions of sex, and are immortal, and are not worn out, by the chills of age—it follows, as a consequence, that the world should be full of gods, and that countless heavens could not contain their multitude, inasmuch as they are both themselves ever begetting, and the countless multitude of their descendants, always being increased, is augmented by means of their offspring; or if, as is fitting, the gods are not degraded by being subjected to sexual impulses, what cause or reason will be pointed out for their being distinguished by those members by which the sexes are wont to recognise each other at the suggestion of their own desires?
For it is not likely that they have these without a purpose, or that nature had wished in them to make sport of its own improvidence, in providing them with members for which there would be no use. For as the hands, feet, eyes, and other members which form our body, have been arranged for certain uses, each for its own end, so we may well believe that these members have been provided to discharge their office; or it must be confessed that there is something without a purpose in the bodies of the gods, which has been made uselessly and in vain.
Source: Against the Heathen (New Advent)