"Well, one measure of a good life, I think, is to be engaged in projects that one thinks are meaningful and worthwhile. So I would put the emphasis of a good life on activity, on the walk rather than the destination, and I think that most of the things that any of us do that are really valuable and really important are projects that we really shouldn't expect to be completed in our lifetime because if they could completed in our lifetime, they probably wouldn't be so important that we should devote our lives to them."