Another example is the work of Darwin, who spent half his life collecting interesting facts about animals and plants. If he had stopped there, his name might not be known today. What he did was suggest a way in which all these facts could be explained. It was an hypothesis which could be, and was, tested in every way possible. It is well known now that the theory of evolution by natural selection best explains the way the living world has come to be as we see it. Again, real science was built on a collection of facts which needed an explanation. The philosophy of science is about testing hypotheses, rather than collecting facts, though facts are the basis of all science.