"Or, rather, it was not he, but an associate, called by him the Physician of Aleppo, who discovered it.

This man was the pupil of the learned Rhazes, and the tutor of the equally learned Avicenna, the link, in fact, between them; but his name, for some reason, perhaps because he mixed with his practice a greater degree of mysticism than was approved by the Arabian schools of the next generation, has not come down to us.

This man identified the product which had defied Ibn Jasher's tests with a substance even then considered by most to be fabulous, or to be extracted only from the horn of the unicorn if that animal existed.

That it had some of the properties of the fabled substance, he proceeded to prove to the satisfaction of Ibn Jasher by curing of a certain incurable disease five persons." "No more than five ?" "No." "Why ?" "The substance was exhausted." Blondel gasped.

"Why did he not make more ?" he cried.