Philosopher’s stone as pictured in Michael Maier’s Atalanta Fugiens Emblem 21.
According to legend the Philosopher’s Stone is a tool in alchemy capable of turning base metals into gold and is believed to be the elixir of life promising health and immortality. Legend states that the thirteenth century Saint Albertus Mangus had discovered the tool and passed it on to Saint Thomas Aquinas. The 17th century alchemy textbook Mutus Liber (Silent Book) by Isaac Baulot supposedly gives the instructions on how to create the Philosopher’s Stone, however it is outlined in a series of 15 mystical illustrations (called plates) which have yet to be accurately translated.
See: McLean, Adam. A Commentary on the Mutus Liber (Hermetic Research Series). Grand Rapids, Michigan: Phanes Press, 1991.