Everything you need to know about the greatest mystery in the universe. The Book of Time is a complete guide to one of the most important, paradoxical and truly mind-bending subjects there is. It explores every aspect of time, including how it works in the natural world and in our bodies, its significance in religion and philosophy, how we measure it and how it has been essential to our scientific understanding of the universe and everything in it. Five sections of insightful text, color photographs and sidebars call on social and political history, science, religion, philosophy, psychology, physics, astronomy, commerce and the natural world to explore time from different perspectives, such as: * How time has been perceived through history, and why a minute can seem like an hour or an hour can seem like a second * How our experience of time is linked to the natural world -- the sun, the moon, the tides, the seasons * When, why and how humans organized time into calendars, time zones and other arbitrary categories * How humans have measured time mechanically, from primitive water clocks and sundials to atomic clocks * How time is central to our quest to understand the universe and everything in it, including time travel and other unsolved mysteries. Time can be billions of years or billionths of a second, but it is always passing ... Or is it? The Book of Time is a fascinating account of a universal mystery.