 Gleason 's entire academic career was at Harvard , from which he retired in 1992 . His numerous academic and scholarly leadership posts included chairmanship of the Harvard Mathematics Department and Harvard Society of Fellows , and presidency of the American Mathematical Society . He continued to advise the United States government on cryptographic security , and the Commonwealth of Massachusetts on math ­ e ­ mat ­ ics education for children , almost until the end of his life . 
