Alchemy is an ancient branch of natural philosophy, a philosophical and protoscientific tradition. Alchemists attempt to purify, mature, and perfect certain materials. Common aims are chrysopoeia, the transmutation of [I]base metals[/I] (e.g., lead) into [I]noble metals[/I] (particularly gold); the creation of an elixir of immortality; the creation of panaceas able to cure any disease; and the development of an alkahest, a universal solvent. The perfection of the human body and soul is thought to permit or result from the alchemical magnum opus and the achievement of gnosis.