Ctesibius was a very smart man who lived a long time ago in ancient Greece. He was known for being an inventor and scientist who made all sorts of cool things that helped people in their daily lives.
One of his biggest inventions was the water clock. This was a special device that used water to tell time. Imagine a big bucket of water with a small hole at the bottom. As the water dripped out of the hole, it would make a noise and the timekeeper would know how much time had passed.
Ctesibius also invented a pump that could move water from one place to another. This was a really big deal because it meant that people could get water from farther away than they could before. This was especially helpful in places where water was scarce.
He also came up with a way to make an automatic flute player. This was a special machine that could play music all by itself. It had little pipes that air would flow through, and buttons that could be pushed to make different notes and tunes.
Overall, Ctesibius was a really clever person who invented things that helped people in many ways. He is remembered as one of the great thinkers of ancient times, and his inventions are still inspiring people today.