caffeine

via an old gladwell article on caffeine:

Paul Hoffman, in "The Man Who Loved Only Numbers," writes of the legendary twentieth-century mathematician Paul Erdös that "he put in nineteen-hour days, keeping himself fortified with 10 to 20 milligrams of Benzedrine or Ritalin, strong espresso and caffeine tablets. 'A mathematician,' Erdös was fond of saying, 'is a machine for turning coffee into theorems.'"