An important scientific innovation rarely makes its way by gradually winning over and converting its opponents: it rarely happens that Saul becomes Paul. What does happen is that its opponents gradually die out, and that the growing generation is familiarized with the ideas from the beginning: another instance of the fact that the future lies with the youth.
[Often paraphrased as "Science progresses one funeral at a time".]
Scientific Autobiography and Other Papers. New York: Philosophical library, 1950, p. 33, 97