People have always struggled with time and their ability to measure it.
Time structures their lives and separates the young from the old.
Because time has such a stranglehold on their changing lives, they look to the constancy of mechanical objects to mark its progress. The first timekeepers, invented around 3500 BC, tracked the sun's shadow, much like a simple sun dial. The first spring-based clock was invented in 1510. Some years later, Galileo noticed that pendulums also had periodic behavior, and in 1656 the first pendulum clock was built. Over the centuries, several other clocks were designed to keep time with everything from quartz crystals, to atomic oscillations, to the flow of electricity.