" The Age of Intellect is accompanied by surprising advances in natural science. In the ninth century, for example, in the age of Mamun, the Arabs measured the circumference of the earth with remarkable accuracy. Seven centuries were to pass before Western Europe discovered that the world was not flat. Less than fifty years after the amazing scientific discoveries under Mamun, the Arab Empire collapsed. Wonderful and beneficent as was the progress of science, it did not save the empire from chaos. "

― John Bagot Glubb , The Fate of Empires and Search for Survival