It is the fine dream of the greatest of the Poets, that Hell, become useless, is to be closed at length, by the aggrandizement of Heaven; that the problem of Evil is to receive its final solution, and Good alone, necessary and triumphant, is to reign in Eternity. So the Persian dogma taught that AHRIMAN and his subordinate ministers of Evil were at last, by means of a Redeemer and Mediator, to be reconciled with Deity, and all Evil to end. But unfortunately, the philosopher forgets all the laws of equilibrium, and seeks to absorb the Light in a splendor without shadow, and movement in an absolute repose that would be the cessation of life. So long as there shall be a visible light, there will be a shadow proportional to this Light, and whatever is illuminated will cast its cone of shadow. Repose will never be happiness, if it is not balanced by an analogous and contrary movement. This is the immutable law of Nature, the Eternal Will of the JUSTICE which is GOD.
The Qanun was translated into Latin as Canon medicinae by Gerard of Cremona . (Confusingly there appear to have been two men called Gerard of Cremona, both translators of Arabic texts into Latin. Ostler states that it was the later of these, also known as Gerard de Sabloneta, who translated the Qanun (and other medical works) into Latin in the 13th century.)  The encyclopaedic content, systematic arrangement, and combination of Galen's medicine with Aristotle's science and philosophy helped the Canon enter European scholastic medicine. Medical scholars started to use the Canon in the 13th century, while university courses implemented the text from the 14th century onwards.  The Canon ' s influence declined in the 16th century as a result of humanists' preference in medicine for ancient Greek and Roman authorities over Arabic authorities, although others defended Avicenna's innovations beyond the original classical texts. It fell out of favour in university syllabi, although it was still being taught as background literature as late as 1715 in Padua.