One biographer describes Darwin as someone who kept thinking about the same questions long after others would move on to different—and no doubt easier—problems: The normal response to being puzzled about something is to say,“I’ll think about this later,” and then, in effect, forget about it. With Darwin, one feels that he deliberately did not engage in this kind of semi-willful forgetting. He kept all the questions alive at the back of his mind, ready to be retrieved when a relevant bit of data presented itself.
