Alexander Graham Bell Quote
I dare say you have all heard of that celebrated painter who would never allow any one to mix his colors for him. He always insisted on doing that himself, and at last one of his students. whose curiosity had been aroused. said: "Professor, what do you mix your colors with?" "With brains, sir," said the professor. Now. that is what we have to do with our observations.
'Discovery and Invention' by Alexander Graham Bell, The National Geographic Magazine, Vol. 25 (1924)