Peter says that he found learned men even from Britain pursuing astronomy.

All learned men, no matter from what country they came, or what their religious views, were welcomed.

The khalif had in his palace a manufactory of books, and copyists, binders, illuminators.
He kept book-buyers in all the great cities of Asia and Africa.

His library contained four hundred thousand volumes, superbly bound and illuminated.
Throughout the Mohammedan dominions in Asia, in Africa, and in Spain, the lower order of Mussulmen entertained a fanatical hatred against learning.

Among the more devout--those who claimed to be orthodox--there were painful doubts as to the salvation of the great Khalif Al-Mamun--the wicked khalif, as they called him--for he had not only disturbed the people by introducing the writings of Aristotle and other Greek heathens, but had even struck at the existence of heaven and hell by saying that the earth is a globe, and pretending that he could measure its size.