Professor Lang's last lecture was to the number theory seminar at Berkeley on Diophantine approximation. While his enthusiasm for the subject was evident, I could only describe the talk as long-winded and bogged down with technical details, and I left at five past, which was five minutes later than the talk was scheduled to end. Later I learned his talk went overtime by no less than half an hour.
Serge Lang died September 12, 2005. Those who encountered him regularly will no doubt remember debating him over his denial of the link between HIV and AIDS until it becomes a one-sided shouting match rising to the inevitable "You can't tell a fact from a hole in the ground!" Even in mathematics his style of interaction was famously combative--he may have told you that your ignorance of the "heat kernel" is a grievous omission in your studies--but behind the fury was the rapture of someone who deeply loves his art.