The philosophers’ stone or stone of the philosophers () is a legendary alchemical substance said to be capable of turning base metals such as lead into gold () or silver. It was also sometimes believed to be an elixir of life, useful for rejuvenation and possibly for achieving immortality; for many centuries, it was the most sought-after goal in alchemy. The philosophers’ stone was the central symbol of the mystical terminology of alchemy, symbolizing perfection at its finest, enlightenment, and heavenly bliss. Efforts to discover the philosophers’ stone were known as the Magnum Opus (“Great Work”).