Under the enlightened rule of the Buyid dynasty (945-1055 AD), the Islamic world witnessed an unequalled cultural renaissance. The main expression of this renaissance was a philosophical humanism that embraced the scientific and philosophical heritage of Classical Antiquity as a cultural and educational ideal. Along with this philosophical humanism, a literary humanism was cultivated by litterateurs, poets and government secretaries. This renaissance was marked by a powerful assertion of individualism in the domains of literary creativity and political action. It thrived in a remarkably cosmopolitan atmosphere. Baghdad, the centre of the Abbasid Empire and of Buyid rule, was the rendezvous for scholars from far and wide, of diverse cultural backgrounds. Philosophers belonged to a class of their own, transcending particular loyalties, united by the pursuit of the truth and the love of reason. This work is an investigation into the nature of the environment in which the cultural transformation took place and into the cultural elite who were its bearers. After an extensive introductory section setting the stage, it deals with the main schools and circles and with the outstanding individual representatives of this renaissance.