Alan was such an unfailingly friendly person. We first met in an elevator more than twenty years ago when he mistook me for a fellow student. Later we became colleagues. Never once, I think, did our paths cross without his coming up with something cheerful to say, something that made the day a bit better. I called him “Monsieur le Baron,” because one of his distant ancestors in Haiti had been made a baron. But he was a bit of a prince, too.