Heraclitus believed fire to be the primordial element, out of which everything else had arisen. Thales, the reader will remember, thought everything was made of water; Anaximenes thought air was the primitive element; Heraclitus preferred fire. At last Empedocles suggested a statesmanlike compromise by allowing four elements, earth, air, fire and water. The chemistry of the ancients stopped dead at this point. No further progress was made in this science until the Mohammedan alchemists embarked upon their search for the philosophers stone, the elixir of life, and a method of transmuting base metals into gold.p. 43.