“I believe that the clue to his mind is to be found in his unusual powers of continuous concentratedintrospection. A case can be made out, as it also can with Descartes, for regarding him as an accomplishedexperimentalist. Nothing can be more charming than the tales of his mechanical contrivances when he was aboy. There are his telescopes and his optical experiments, These were essential accomplishments, part of hisunequalled all-round technique, but not, I am sure, his peculiar gift, especially amongst his contemporaries.His peculiar gift was the power of holding continuously in his mind a purely mental problem until he hadseen straight through it. I fancy his pre-eminence is due to his muscles of intuition being the strongest andmost enduring with which a man has ever been gifted. Anyone who has ever attempted pure scientific orphilosophical thought knows how one can hold a problem momentarily in one's mind and apply all one'spowers of concentration to piercing through it, and how it will dissolve and escape and you find that whatyou are surveying is a blank. I believe that Newton could hold a problem in his mind for hours and days andweeks until it surrendered to him its secret. Then being a supreme mathematical technician he could dress itup, how you will, for purposes of exposition, but it was his intuition which was pre-eminently extraordinary- 'so happy in his conjectures', said De Morgan, 'as to seem to know more than he could possibly have anymeans of proving'. The proofs, for what they are worth, were, as I have said, dressed up afterwards - theywere not the instrument of discovery.””