The prophet Muhammad and the early Islamic community radically redefined the concept of time that they had inherited from earlier religions' beliefs and practices. This new temporal system, based on a lunar calendar and era, was complex and required sophistication and accuracy. From the ninth to the sixteenth century, it was the Muslim astronomers of the Ottoman, Safavid, and Mughal empires, and not those of Europe, who were responsible for the major advances in mathematics, astronomy, and astrology. Stephen Blake's fascinating study compares the Islamic concept of time, and its historical...