"The greatest show on Earth is life itself, in its diversity, complexity, beauty, in the incredible variety of species engaged in its role in this world. We see all this through evolution, and evolution itself through natural selection. The book is devoted to the evidence of evolution, indicating that evolution is a fact. Dawkins is an atheist, an anti-clerical humanist, a skeptic, a rationalist who shares the ideas of the Enlightenment. In the media, he is often called "Darwin's Rottweiler" by analogy with the English biologist T. H Huxley, nicknamed "Darwin's Bulldog" for his speeches in defense of natural selection.