The information system contained in DNA is so powerful and so elegant that it far outstrips anything that has been invented by way of computers. Dawkin's description of it aims to bring out the inspirational quality of our understanding of Darwinian life. The river of the title is the river of information carried through time in DNA, flowing and branching like a real river, and giving rise to new species as it does so. This book provides an explanation of the process of evolution, as illuminated by the theory of Darwinian natural selection.