T. J. De Boer 
The History of Philosophy in Islam [EPUB ebook] 

First published in 1901, ‘The History of Philosophy in Islam’ is a complete summary of the flowering of Islamic philosophy in the late middle ages. 
Medieval Islamic civilisation at its height was a centre of learning, and its philosophers were no exception. Islamic philosophers grappled with issues such as free-will, causality and the nature of reality. Some of these figures are still well-known, such as Ibn Sina (Avicenna), Ibn Roshd (Averroes), the Sufi Gazali, and Kindi.