"Whatever contributions I have made have largely been something other than what I started out looking for, as is the case with many contributions in science. Basically, there are lots of important issues and lots of hints that come your way. I have had that opportunity many times, that when you are concentrating on an issue in a broad perspective, some clue comes along, a hook that gives you a unique insight that you wouldn't otherwise have had."
“In retrospect it seems clear – we didn’t know how to eradicate smallpox when we started. But this was not a negative. It was a characteristic of all unsolved problems. We are always faced with making sufficient decisions based on insufficient information. If we had waited until all the answers were available, the work on smallpox eradication would never have started – selecting the target helped develop the appropriate tools and strategy
“My guiding philosophy has always been, 'Chance favors a prepared mind,' which is a quote from Louis Pasteur. My own complement to that: 'If a research project turns out as expected, you haven't learned anything.'”