Or Ben Franklin, contemplating his vegetarianism:

But I had formerly been a great Lover of Fish, & when this came hot out of the Frying Pan, it smelt admirably well. I balanc'd some time between Principle & inclination: till I recollected, that when the Fish were opened, I saw smaller Fish taken out of their Stomachs:--Then, thought I, if you eat one another, I don't see why we mayn't eat you. So I din'd upon Cod very heartily and continu'd to eat with other People, returning only now & then occasionally to a vegetable Diet. So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for every thing one has a mind to do