For Sacks, wrestling with the meaning of experience — his own, his patients’ — continued until the very end. One folder, with the jaunty title “Some Deaths I’ve Liked,” contains the wry and humorous last words of scientists and others, starting with his brother Michael, whose lifelong struggle with schizophrenia greatly affected Sacks. In his telling, Michael sat up abruptly in his hospital gurney and announced, “I’m going outside to smoke a cigarette,” before immediately falling dead.