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Public DomainGeber
 Geber, or Abu Musa Jabir ibn Hayyan al azdi  (721-815), was a man of many talents.  Engineer, physician, geologist, astronomer and philosopher, he was also called by some the "father of chemistry".  He was one of the earliest practising alchemists, and his ideas strongly influenced later European students.  He believed that the alchemical elements could be classified according to their internal and external qualities of hotness, coldness, moistness and dryness.  So lead was cold and dry externally, while gold was hot and moist.  By rearranging these qualities, he argued, it would be possible to transmute one element into another.