... Ulam, a newly appointed professor at the University of Southern California, awoke to find himself unable to speak. A few hours later, he underwent a dangerous surgical operation after the diagnosis of encephalitis... In time, however, some changes in his personality became obvious to those who knew him... [H]is ideas, which he spouted out at odd intervals, were fascinating beyond anything I have witnessed before or since. However, he seemed to studiously avoid going into details... [H]e came to lean on his unimpaired imagination for his ideas, and on ... others for technical support... A crippling technical weakness coupled with an extraordinarily creative imagination is the drama of Stan Ulam.