Philosopher's Stone

a substance much sought by the alchemists. It was reputed to have the power to change base metals into gold and silver. So long as it appeared to men that salt, sulphur, and mercury (representing earth, air, and water), and fire were the constituents of all things visible, the search for an additional substance, which on being roasted with a base metal would make gold or silver, was not altogether foolish. Many an alchemist practiced imposture and deceit, and many an honest life was worn out in the vain quest, in attempting the impossible, to find the philosopher's stone. See Alchemy