His site says he stopped email on January 1, 1990. This would have been before his formal retirement in 1992 or 1993 which was also unusual in that he was only

His site says he stopped email on January 1, 1990. This would have been before his formal retirement in 1992 or 1993 which was also unusual in that he was only in his early 50s at the time. I agree that his is not a general case. Quod licet Iovi, non licet bovi and all that. Someday I would like to know how people like him develop and maintain that level of drive and focus. I've been able to do it for a few weeks at a time, maximum before bonking hard.