The importance of the "Koran" lies in the fact that it is a religious book of the East, read and stored in the memory of a hundred millions of people of different races and civilizations, inhabiting countries extending from the western borders of China to the pillars of Hercules. It is considered by the Mohammedan to contain all the knowledge and all the literature necessary for men. When it was demanded of Mohammed to confirm the authority of his mission by some work of wonder, he pointed to the "Koran, " and exclaimed, "Behold the greatest miracle of all." The learned men of Alexandria asked the Caliph Omar to give to them the vast library at Alexandria. "If those books, " he replied, "contain anything which is contrary to the 'Koran' they deserve to be destroyed. If they contain what is written in the 'Koran, ' they are unnecessary."