"My theory was that we are all fundamentally 'multiple personalities', beginning with the baby and the child, and slowly developing into more complex selves. If, for some reason, we abruptly cease to develop -- through some trauma that undermines self-confidence -- all those potential personalities are stunted and repressed. And some accident or violent shock may give one of them the opportunity to 'take over'. This suggests, of course, that in some mysterious sense, our 'future' personalities are already there, in embryo, so to speak, and that they also develop as we mature. We move from personality to personality, as we might climb a ladder. The Beethovens and Leonardos got further up the ladder than most of us; yet even they failed to reach the top, as we can see if we study their lives."