Long ago people could not tell the time. They woke when there was light and slept when it was dark. Then they started to guest the time during the day by looking at shadows. After that they started to make their own objects to cast a shadow. They put a stick or a stone on the floor and called it sundials. After that the Greeks used sand and the Romans used candles. The real clocks were made in the 24th century. The early ones had a huge rock and soon after the lead weights were made they used a pendulum.