No amount of study of present forms [of life] would permit us to infer [the existence of] dinosaurs

The whole business was like a child's toy that you could buy at the dime store, all built in this wonderful way that you could explain in Life magazine so that really a five-year-old can understand what's going on...This was the greatest surprise for everyone.

Any living cell carries with it the experience of a billion years of experimentation by its ancestors.

[Physicists] feel that the field of bacterial viruses is a fine playground for serious children who ask ambitious questions.

If you're too sloppy, then you never get reproducible results, then you never get reproducible results, and then you never can draw any conclusions but if you are just a little sloppy, then when you see something startling, you nail it down. So I called it the Principle of Limited Sloppiness.