‘Of course, you have to wonder about where the wood came from.

Well, it came from a tree, and the substance of a tree is carbon. Where did that come from? It comes from the air, it’s carbon dioxide from the air. People look at trees and they think they come out of the ground but really trees come out of the air. The carbon dioxide in the air goes into the tree and it changes it; it kicks out the oxygen, pushing the oxygen away from the carbon and leaving the carbon substance with water. (The water comes out of the ground, but how did it get in there? It came out of the air, down from the sky. So in fact most of a tree is out of the air. There’s just a little bit from the ground, some minerals, and so forth.) Now as we know, oxygen and carbonstick very, very tight. How is it that the tree is so smart as to manage to take the carbon dioxide which is the carbon and oxygen so nicely combined, and undo it that easily?” ‘Ah!” you say “life has some mysterious force…” But no – the sun is shining, and it’s the sunlight that comes down and knocks this oxygen away from the carbon, and now the oxygen is some terrible by-product which the tree splits back into the air, leaving the carbon and the water and stuff to make the substance of the the tree.'

- Richard Feynman