What is the stuff made of?

Answer 1

A very long time ago - about two and a half thousand years ago - philosophers in ancient Greece wondered about the world. And they wondered about what everything was made of.

One philosopher, called Anaximenes, thought that everything was air. Things like earth and water don't seem to be air, do they? Still, Anaximenes thought that earth and water are what you get if you squash air up. Squash air up enough and it turns into water. Squash it up some more and you get earth.

Before Anaximenes, another philosopher, Thales, supposed that everything was water.

And after Anaximenes, there came Heraclitus, who thought that, deep down, the world was fire.

Eventually, a philosopher called Empedocles decided that none of these theories was quite right. He said the world was amde up of not one but four elements - earth, air, fire and water.

The theory that the world is made up of these four elements became popular and lasted for a long time - more than two thousand years.