In very early time, Man attributed the wonders of nature to the gods. However, around the first century before the birth of Christ, there was an intellectual awakening in the ancient Greek colonies. The philosophers of the time realized that the Universe exhibited an order, and followed certain rules. Around 450 BC, Empedocles, an ancient Greek philosopher and poet, first put forward the idea that all matter is composed of four essential elements- Fire, Air, Water and Earth. He used a clepsydra, a vessel with a hole at the bottom, and one at the top, to prove that air existed. He was one of the first to conduct an experiment to prove a scientific theory.
