This New Yorker story on the history of vegetarianism ends with the following quotation of Franklin:
Our People set about catching Cod, & haul’d up a great many. Hitherto I had stuck to my Resolution of not eating animal Food; and on this Occasion, I consider’d . . . the taking every Fish as a kind of unprovok’d Murder, since none of them had or ever could do us any Injury that might justify the Slaughter. All this seem’d very reasonable. But I had formerly been a great Lover of Fish, & when this came hot out of the Frying Pan, it smeled 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 everything one has a mind to do. [Italics in original; paragraph break mine.]
(Via Arts & Letters Daily.)