Late in life, Isaac Newton suffered a nervous breakdown, 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, and that may have been exactly what it did to Newton.
Al-Kindi is unanimously hailed as the "father of Islamic or Arabic philosophy" for his synthesis, adaptation and promotion of Greek and Hellenistic philosophy in the Muslim world. As an advanced chemist, he debunked the myth that simple, base metals could be transformed into precious metals such as gold or silver.