70 But why do I speak of these trivial things? The immortal gods themselves, whose temples you now enter with reverence, whose deity you suppliantly adore, did they not at certain times, as is handed down by your writings and traditions, begin to be, to be known and to be invoked by names and titles which were given to them? For if it is true that Jupiter with his brothers was born of Saturn and his wife, before Ops was married and bore children Jupiter had not existed both the Supreme and the Stygian, no, nor the lord of the sea, nor Juno, nay more, no one inhabited the heavenly seats except the two parents; but from their union the other gods were conceived and born, and breathed the breath of life.
So, then, at a certain time the god Jupiter began to be, at a certain time to merit worship and sacrifices, at a certain time to be set above his brothers in power. But, again, if Liber, Venus, Diana, Mercury, Apollo, Hercules, the Muses, the Tyndarian brothers, and Vulcan the lord of fire, were begotten by father Jupiter, and born of a parent sprung from Saturn, before that Memory, Alcmena, Maia, Juno, Latona, Leda, Dione, and Semele also bore children to Diespiter; these deities, too, were nowhere in the world, nor in any part of the universe, but by Jupiter's embraces they were begotten and born, and began to have some sense of their own existence.
So then, these, too, began to be at a certain time, and to be summoned among the gods to the sacred rites. This we say, in like manner, of Minerva. For if, as you assert, she burst forth from Jupiter's head ungenerated, before Jupiter was begotten, and received in his mother's womb the shape and outline of his body, it is quite certain that Minerva did not exist, and was not reckoned among things or as existing at all; but from Jove's head she was born, and began to have a real existence.
She therefore has an origin at the first, and began to be called a goddess at a certain time, to be set up in temples, and to be consecrated by the inviolable obligations of religion. Now as this is the case, when you talk of the novelty of our religion, does your own not come into your thoughts, and do you not take care to examine when your gods sprung up—what origins, what causes they have, or from what stocks they have burst forth and sprung? But how shameful how shameless it is to censure that in another which you see that you do yourself—to take occasion to revile and accuse others for things which can be retorted upon you in turn!
Source: Against the Heathen (New Advent)