Cambridge, Mass. ONE morning in January 1997, I walked into my office at a nonprofit group here after a visit to my hometown, Calcutta. A very senior colleague, whom I would have, until then, characterized as being the “sensitive” sort, greeted me: “Welcome back. And how is everyone in Calcutta — still starving and being looked after by Mother Teresa?” At first I thought this might be a bad attempt at humor, but I soon realized that my colleague was seriously inquiring about my city’s suffering humanity and its ministering angel — the only images Calcutta evoked for him and...