|Finally, the florescence of Islamic science began to fade. Needless to say, scientific activity continued to flourish, but at a much slower pace. Students eager to devote their entire life to search after knowledge were harder to come by and those being trained in various branches of knowledge, such as mathematics and astronomy, were in no way comparable with the giants of the previous centuries. There no longer appeared the equals of Khwarazmi, Kuhi, Abu al-Wafa, Sijzi, Ibn Haytham, Abu al-Jud, Biruni and Ibn Sina. The seeds of anti-intellectualism sown by certain schools over the span of the past few centuries were finally coming to fruition, especially the victory of Ash`arism and its alliance with temporal power. In fact, the evil consequences of this movement have been compared with the destruction wrought by the hordes of savage Mongols whose invasion came in the heels of this decline. The Crusades, in spite of their consequent insecurity and dislocation, which disrupted scientific activity in certain parts of the Islamic world, were in no way comparable to the convulsion caused by the Mongol onslaught.
Throughout history, no civilization has had to cope with such intense devastation. Only a man of the stature of Nasir al-Din Tusi would have been capable of salvaging some remnants of that great culture. The scientific resurgence of the 7th/13th century and the rise of such personalities as Kamal al-Din b. Yunus, Athir al-Din Abhari, Muhyi al-Din Maghribi and Nasir al-Din Tusi, with their treatises on conic sections, parallel lines and the principle of parallelism, elaboration of the Euclidean geometry and the ideas of the Almagest, was the result of a short-lived mathematical renaissance.