stimulating introduction to a school of thinking and a body of research that is not widely known or easily accessible to us. His attempt to provide a unify ing theory of sensory receptor mechanisms based on evolutionary principles is unique and imaginative. Among the joys of a career in science is the opportunity to rub shoulders with people of outstanding intellectual power and, with luck, to have the privilege of their friendship. In May of 1979 I visited the U.S.S.R. as a guest lecturer in chemical senses. During the 8 days that I spent in the beautiful city of Leningrad I had the great...