The recognition of our own mistakes should not benefit us any more than the study of our successes. But there is a natural tendency in all men to avoid punishment. When you associate certain mistakes with a licking, you do not hanker for a second dose, and, of course, all stock-market mistakes wound you in two tender spots — your pocket book and your vanity. But I will tell you something curious: A stock speculator sometimes makes mistakes and knows that he is making them; and after he makes them he will ask himself why he made them; and after thinking over it cold-bloodedly a long time after the pain of punishment is over he may learn how he came to make them, and when, and at what particular point of his trade; but not why. And then he simply calls himself names and lets it go at that.
Of course, if a man is both wise and lucky, he will not make the same mistake twice. But he will make any one of the ten thousand brothers or cousins of the original. The Mistake family is so large that there is always one of them around when you want to see what you can do in the fool-play line.
– Reminiscences of a Stock Operator, by Edwin Lefèvre, 1923