Philosopher's Stone. One of the most prominent features of the creed of the alchemists [Alchemy, Chemistry] was the belief in the trans mutability of all metals. The point aimed at then was, of course, the conversion of the commoner metals into the more precious gold. The agency by which this desired result was to be effected was the philosopher's stone, of the existence of which not a doubt was entertained, and many of the philosophers of the Middle Ages - e.g. Albertus Magnus, Roger Bacon - spent much time in the search for this ignis fatuus. In this respect the philosopher's stone could act without limit, and an indefinite quantity of gold could be prepared through the agency of the smallest amount of this wonderful substance. It was further endowed with other miraculous powers, being capable of curing all bodily and physical infirmities, and hence of prolonging life almost indefinitely.