In this rich selection from Darwin's most important and relevant works, Glick and Kohn provide the reader with a map of sorts by which to navigate the ins and outs of the development of the theory of natural selection. A concise general introduction lays out Darwin's theory, which is followed up in the chapter introductions. Each chapter ends with an excerpt from Darwin's correspondence, commenting on the work in question, its significance, impact, and reception. In addition, two essential appendices are included - the first three chapters from Malthus, On Population, which gave Darwin the idea for natural selection, and the paper by Wallace that motivated Darwin to abandon the "Big Species Book" and write Origin of Species.