From BENJAMIN FRANKLIN's AUTOBIOGRAPHY

I believe I have omitted mentioning that, in my first voyage from Boston, being becalmed off Block Island, our people set about catching cod, and hauled up a great many. Hitherto, I had stuck to my resolution of not eating animal food, and on this occasion I considered, with my master Tyron, the taking of every fish as a kind of unprovoked murder, since none of them had, or ever could do us any injury that might justify the slaughter.

All this seemed very reasonable. But I had formerly been a great lover of fish, and when this came hot out of the frying-pan, it smelled admirably well. I balanced some time between principle and inclination, till I recollected that, when the fish was 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 dined upon cod very heartily, and continued to eat with other people, returning only now and 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 everything one has a mind to do.