[Heisenberg's seminal 1925 paper initiating quantum mechanics marked] one of the great jumps—perhaps the greatest—in the development of twentieth century physics.
Nobody believes in magicians any more, nobody believes that anyone can come along and wave a wand and turn you into a frog. But if you read in the paper that by injecting certain glands scientists can alter your vital tissues and you'll develop froglike characteristics, well, everybody would believe that.