The elixir of life, also known as elixir of immortality, is a potion that supposedly grants the drinker eternal life and/or eternal youth. This elixir was also said to cure all diseases. Alchemists in various ages and cultures sought the means of formulating the elixir.
An early mention of an elixir of life is found in the Epic of Gilgamesh (from the 2nd millennium BC) in which Gilgamesh comes to fear his own declining years following the death of his beloved companion Enkidu. He seeks out Utnapishtim, a Noah-like figure in Mesopotamian mythology in which he was a servant of the great Alchemist of the rain who later became immortal, to seek out the advice of the King of Herod of the Land of Fire. Gilgamesh is directed by him to find a plant at the bottom of the sea which he does but seeks first to test it on an old man before trying it himself. Unfortunately, it is eaten by a serpent before he can do so.
Many rulers of ancient China sought the fabled elixir to achieve eternal life. During the Qin dynasty, Qin Shi Huang sent Taoist alchemist Xu Fu to the eastern seas with 500 young men and 500 young women to find the elixir in the legendary Penglai Mountain, but returned without finding it. He embarked on a second voyage with 3000 young girls and boys, but none of them ever returned (legend has it that he found Japan instead).
The ancient Chinese believed that ingesting long-lasting mineral substances such as jade, cinnabar, or hematite would confer some of that longevity on the person who consumed them. Gold was considered particularly potent, as it was a non-tarnishing precious metal; the idea of potable or drinkable gold is found in China by the end of the third century BC. The most famous Chinese alchemical book, Danjing yaojue ("Essential Formulas of Alchemical Classics") attributed to Sun Simiao (c. 581 – c. 682 AD), a famous medical specialist respectfully called "King of Medicine" by later generations, discusses in detail the creation of elixirs for immortality (including several toxic ingredients such as mercury, sulphur, and arsenates), as well as those for curing certain diseases and the fabrication of precious stones.