It is often said that an interest in the history of one's subject is, in a scientist, a sign of failing powers. If so, then my powers must have begun to fail very early, for I cannot remember a time, once I had learned to read for pleasure, when I was not fascinated by the personalities of those who had made great discoveries and by the circumstances in which those discoveries were made. So you' II find among my publications a number of occasional pieces in which some eminent scientist or some important scientific event is subjected to scrutiny, regrettably the far from expert scrutiny that lies within the purchase of a very amateur historian. Some of these pieces were prompted by invitations from editors in urgent need of an obituary notice or, less often, of a more extended biographical memoir. It was an invitation of this kind that set me to work on the scientific life of Basil D., who, some 30 years ago, had made a discovery whose importance can hardly be exaggerated. I remember being all but stunned by the paper when it appeared, for it showed, wholly unexpectedly and contrary to all our assumptions, that cells derived from our own bodies could somehow (we didn't find out how until very much later) exchange genes. Of course, such a revolutionary idea was received at first with extreme scepticism, but it was quickly confirmed and Basil was catapulted to a stardom that few scientists ever achieve.