The clepsydra, or water clock, is an ancient timekeeper that operates by measuring the regulated flow of liquid into or out of a vessel. It is believed to have been used in Egypt as early as 2,000 BCE, making it one of the earliest known time-measurement devices. Early water clocks were calibrated with a sundial, and they remained the most accurate timekeeping devices until the invention of the pendulum clock in the 17th century. When did knowing the time become important to the common man? Discuss
Source: The Free Dictionary