Deciding when you reach the point of diminishing return in one direction and you really ought to be picking up your gear and moving over to another sector on the advancing front. So I have, in a sense, been an opportunist. The one common thread in my scientific career has been the devotion to one group of organisms, the ants, which I set out to learn thoroughly for the pleasure of it, but also developed for the richness of new material and opportunities for discovery that they could provide. Given that as a kind of anchor, and given evolution as a grand organizing theme for developing research programs, I began with the relatively simple program, actually in my teens, of studying ants and their classification and a little bit of the natural history.