I spent a few minutes investigating, and found lots of quotations by non-scientists about science and scientists. In terms of quotable quotations -- the kind one might put in an email sig file, for example, if one were that sort of person -- I wonder what the quotable scientists : quotable non-scientists is for famous quotations about Science.
If you search the internet for "Who is the most quoted scientist", the answer you get is Bert Vogelstein, cancer researcher. I do not consider being cited the same as being quoted, so, with all due respect to Bert and his gazillion citations, that answer is unsatisfactory.
It wouldn't surprise me if Albert Einstein were the real #1 most quoted scientist, especially since he seems to have spoken mostly in quotations. Richard Feynman is probably high in the ranking as well.
I don't typically find quotations very inspiring, but as I grazed the internet for quotations today I found one I kind of like, mostly because it is a tad more cynical than the average quotation:
If a scientist were to cut his ear off, no one would take it as evidence of a heightened sensibility.
Peter B. Medawar (zoologist, 1915-1987)