Late in life, Newton suffered a nervous breakdown and became known for rather eccentric behavior
But it probably wasn’t his fault. A 1979 examination of Newton’s hair showed astronomical amounts of mercury, probably as a result of all of his alchemy experiments. Too much mercury can drive a man mad, of course, and that may have been exactly what it did to Isaac Newton. Then again, maybe not: the other side of the argument is that Newton never lost his hair (although he was gray by the age of 30 and attributed it to his studies with mercury) and never had bleeding gums, two very prominent symptoms of mercury poisoning.