Designed for use in a broad range of courses in the humanities, Darwin's theory is laid out in a concise general Introduction and followed up in short chapter introductions. Each chapter concludes with an excerpt from Darwin's correspondence, commenting on the work in question, and its significance, impact, and reception. Two short appendixes are includedâthe 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.