Q: What is the difference between a good scientist and a great scientist?
A: The quotations.

Nature uses only the longest threads to weave her patterns, so each small piece of her fabric reveals the organization of the entire tapestry.
R.P. Feynman

New directions in science are launched by new tools much more often than by new concepts. The effect of a concept-driven revolution is to explain old things in new ways. The effect of a tool-driven revolution is to discover new things that have to be explained.
F. Dyson

Everything should be made as simple as possible, but no simpler.
A. Einstein

Once you have eliminated the impossible, whatever remains, however improbable, must be the truth.
A. C. Doyle in "The sign of four"

I have no reason to believe that the human intellect is able to weave a system of physics out of its own resources without experimental labour. Whenever the attempt has been made it has resulted in an unnatural and self-contradictory mass of rubbish.
J. C. Maxwell