18 And as we are now speaking of the animals sacrificed, what cause, what reason is there, that while the immortal gods— for, so far as we are concerned, they may all be gods who are believed to be so— are of one mind, or should be of one nature, kind, and character, all are not appeased with all the victims, but certain deities with certain animals, according to the sacrificial laws? For what cause is there, to repeat the same question, that that deity should be honoured with bulls, another with kids or sheep, this one with sucking pigs, the other with unshorn lambs, this one with virgin heifers, that one with horned goats, this with barren cows, but that with teeming swine, this with white, that with dusky victims, one with female, the other, on the contrary, with male animals?
For if victims are slain in sacrifice to the gods, to do them honour and show reverence for them, what does it matter, or what difference is there with the life of what animal this debt is paid, their anger and resentment put away? Or is the blood of one victim less grateful and pleasing to one god, while the other's fills him with pleasure and joy? Or, as is usually done, does that deity abstain from the flesh of goats because of some reverential and religious scruple, another turn with disgust from pork, while to this mutton stinks? And does this one avoid tough ox-beef that he may not overtax his weak stomach, and choose tender sucklings that he may digest them more speedily?
Source: Against the Heathen (New Advent)