The idea that species are caused by evolution had been proposed before Darwin, but his book gave much evidence, and many were persuaded by it. The book was "On the Origin of Species by means of Natural Selection", published in November 1859. In this book, Darwin wrote about the idea of evolution in general, rather than the evolution of humans. "Light will be thrown on the origin of man and his history", was all Darwin wrote on the subject. Nevertheless, the implication of the theory was clear to readers at the time.