Moreover, the studies of the alchemist may with some propriety be said to have laid the foundation for the latter-day science of chemistry; while astrology was closely allied to astronomy, though its relations to that science are not as intimate as has sometimes been supposed.
Just when the study of alchemy began is undetermined.

It was certainly of very ancient origin, perhaps Egyptian, but its most flourishing time was from about the eighth century A.D.to the eighteenth century.

The stories of the Old Testament formed a basis for some of the strange beliefs regarding the properties of the magic "elixir," or "philosopher's stone." Alchemists believed that most of the antediluvians, perhaps all of them, possessed a knowledge of this stone.
How, otherwise, could they have prolonged their lives to nine and a half centuries?
And Moses was surely a first-rate alchemist, as is proved by the story of the Golden Calf.( 1) After Aaron had made the calf of gold, Moses performed the much more difficult task of grinding it to powder and "strewing it upon the waters," thus showing that he had transmuted it into some lighter substance.
But antediluvians and Biblical characters were not the only persons who were thought to have discovered the coveted "elixir." Hundreds of aged mediaeval chemists were credited with having made the discovery, and were thought to be living on through the centuries by its means.

Alaies de Lisle, for example, who died in 1298, at the age of 110, was alleged to have been at the point of death at the age of fifty, but just at this time he made the fortunate discovery of the magic stone, and so continued to live in health and affluence for sixty years more.

And De Lisle was but one case among hundreds.
An aged and wealthy alchemist could claim with seeming plausibility that he was prolonging his life by his magic; whereas a younger man might assert that, knowing the great secret, he was keeping himself young through the centuries.