In 1838 a strong idea formed into his head. Darwin saw how transmutation worked. Animals that survive longer and have more healthy young are the ones that are more suited to there environment. But he also struggled with the idea because it's against the Christian belief.

By 1858 Darwin had written a quarter of a million words but had not shown anyone. Then he received a letter that encouraged him to go public. It was a letter from his friend Wallace who admired Darwin, he had set off to travel around the world to find his discovery's.It was a letter for advice on how he should publish his book about natural selection. Darwin realised that if he didn't go public, Wallace would get all the credit on his theory! So he decided to treat him fairly.

Darwin finally presented his work along side Wallace to Britains leading natural history body. Which Wallace accepted as fair.

Eventually In 1859 he published his book on "The Origin Of Species By Means Of Natural Selection". He was terrified to publish it and didn't want to be criticised. He didn't want to lose his reputation. All this worry made him quite ill with anxiety. He said that time was "Like living in hell"

The book did get criticism but also many scientists thought highly on it. The book caused lots of debate and it became one of the most important books of history.

Darwin published more books later on and they all became best sellers. In 1882 he died a recluse.