The following is from Elsa Einstein, Albert Einstein's wife, regarding Einstein's development of the theory of general relativity. It's taken from the outstanding book Einstein and Religion by Max Jammer. It's originally taken from Charles Chaplin's autobiography.
The Doctor came down in his dressing gown as usual for breakfast but he hardly touched a thing. I thought something was wrong, so I asked what was troubling him. "Darling," he said, "I have a wonderful idea." And after drinking his coffee, he went to the piano and started playing. Now and again he would stop, making a few notes then repeat: "I've got a wonderful idea, a marvelous idea!" I said: "Then for goodness' sake tell me what it is, don't keep me in suspense." He said: "It's difficult, I still have to work it out."
She told me he continued playing the piano and making notes for about half an hour, then went upstairs to his study, telling her that he did not wish to be disturbed, and remained there for two weeks. "Each day I sent him up his meals," she said, "and in the evening he would walk a little for exercise, then return to his work again. Eventually," she said, "he came down from his study looking very pale. "That's it," he told me, wearily putting two sheets of paper on the table. And that was his theory of relativity."
Thought Of Swami Vivekananda: