The convenience of reason

From Benjamin Franklin: His Autobiography. The first paragraph illustrates an important consequence of human reason. I couldn't resist including the second and third paragraphs for your entertainment.

I believe I have omitted mentioning that, in my first voyage from Boston, being becalm'd 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 consider'd, with my master Tryon, the taking 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 smelt admirably well. I balanc'd some time between principle and 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 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.

Keimer and I liv'd on a pretty good familiar footing, and agreed tolerably well, for he suspected nothing of my setting up. He retained a great deal of his old enthusiasms and lov'd argumentation. We therefore had many disputations. I used to work him so with my Socratic method, and had trepann'd him so often by questions apparently so distant from any point we had in hand, and yet by degrees lead to the point, and brought him into difficulties and contradictions, that at last he grew ridiculously cautious, and would hardly answer me the most common question, without asking first, "What do you intend to infer from that?" However, it gave him so high an opinion of my abilities in the confuting way, that he seriously proposed my being his colleague in a project he had of setting up a new sect. He was to preach the doctrines, and I was to confound all opponents. When he came to explain with me upon the doctrines, I found several conundrums which I objected to, unless I might have my way a little too, and introduce some of mine.

Keimer wore his beard at full length, because somewhere in the Mosaic law it is said, "Thou shalt not mar the corners of thy beard." He likewise kept the Seventh day, Sabbath; and these two points were essentials with him. I dislik'd both; but agreed to admit them upon condition of his adopting the doctrine of using no animal food. "I doubt," said he, "my constitution will not bear that." I assur'd him it would, and that he would be the better for it. He was usually a great glutton, and I promised myself some diversion in half starving him. He agreed to try the practice, if I would keep him company. I did so, and we held it for three months. We had our victuals dress'd, and brought to us regularly by a woman in the neighborhood, who had from me a list of forty dishes to be prepar'd for us at different times, in all which there was neither fish, flesh, nor fowl, and the whim suited me the better at this time from the cheapness of it, not costing us above eighteenpence sterling each per week. I have since kept several Lents most strictly, leaving the common diet for that, and that for the common, abruptly, without the least inconvenience, so that I think there is little in the advice of making those changes by easy gradations. I went on pleasantly, but poor Keimer suffered grievously, tired of the project, long'd for the flesh-pots of Egypt, and order'd a roast pig. He invited me and two women friends to dine with him; but, it being brought too soon upon table, he could not resist the temptation, and ate the whole before we came.