A brief history of timekeeping When humans first started to measure time , the hours of the day were of different lengths. Then the mechanical clock fundamentally changed human life. The history of timekeeping culminates in the invention of the mechanical clock . It was not until the 14th century that people begun to measure time in smaller units. Until then, humans relied on nature to determine the time of the day. In the 6th century, a demand for more accurate time measurement arose in the medieval monasteries of Europe. The monks followed the ancient Greeks and Romans who originally divided the day into 12 hours, and divided each day and each night into twelve equal units - hours. To determine the time of the day, the monks used a variety of timekeeping devices. Historians are unable to determine when exactly the first mechanical clock was invented, but according to researchers the earliest mechanical clocks originated in Europe, at the beginning of the Late Middle A