Although Abu Hamid Muhammad Al-Gazali lived only a short life (1058-1111) he is considered one of the most important thinkers of Islam. This text by Al-Ghazali, written after more than a decade of travel and ascetic contemplation, contends that while Muslim philosophers such as Avicenna boasted of unassailable arguments on theology and physics, they could not deliver on their claims; moreover, many of their assertions really represented disguised heresy and unbelief. Despite its attempted refutation by the 12th-century philosopher Ibn Rushd, Al-Ghazali's work remains influential.