A medieval alchemist in his laboratory seeks the philosophers' stone
(Credit: The Hulton Picture Company)

Pioneered in China in the fourth century BC, it was widely practised in ancient Greece, medieval Islam and early Renaissance Europe, laying the groundwork for modern chemistry. In addition to its transmutatory power, the stone was believed to have the properties of a universal medicine for longevity and immortality. Gold, the metal that does not corrode, symbolises immortality. The Chinese compared the durability of gold to the much-sought immortality of the body. One of their primary goals was the preparation of liquid gold as an elixir. Alchemists included kings and popes, among them Herakleios of Byzantium, James IV of Scotland and Charles II of England.

Chaucer devoted one Canterbury Tale – The Canon’s Yeoman’s – to the pursuit of the stone:

‘I seye, my lord can switch subtiltee
That al this ground on which we been ryding,
Til that we come to Caunterbury toun,
He could al clene turne it up-so-doun,
And pave it al of silver and of gold’.