An ancient tradition holds that Pythagoras discovered the secrets of harmony within a forge when he came across five men hammering with five hammers, producing a wondrous sound. Four of the five hammers stood in a marvelous set of proportions, harmonizing; but there was also a fifth hammer. Pythagoras saw and heard it, but he could not measure it; nor could he understand its discordant sound. Pythagoras therefore discarded it. What was this hammer, such that Pythagoras chose so decidedly to reject it?Since antiquity, -harmony- has been a name for more than a theory of musical sounds; it...