People have always organized their lives by the passing of time. The earliest hunters had to hunt during the hours of daylight. When farming had developed, it was important for farmers to understand the seasons in order to plant their crops at the right time.
Long ago, people realized that the movement of the Sun allowed them to recognize the time of day. They also realized that the movement of the Moon was regular and could be used to give measurements of roughly one month. Modern life is governed much more by time, and we now depend on highly accurate clocks to measure every second of the day.
Picture credit: google