I remember meeting H.M. in the spring of 1967, when he was perhaps 40 years old and I was 16 years his junior. My mentor, Hans-Lucas Teuber, brought him to my tiny office across from the psychology department library at the Massachusetts Institute of Technology. I recall H.M.'s thin, smiling, rather handsome face as he squeezed into the doorway with Teuber, who introduced us as “Don” and “Henry,” as if we might become buddies. I think I called Henry “sir” as we shook hands because he was already a minor M.I.T. celebrity. Teuber assured Henry that he would enjoy taking part in my experiment on sentence comprehension, something he was good at, and excused himself.