Originally published in 1921, this book was written by Major Leonard Darwin (1850–1943), a son of Charles Darwin who was involved in numerous fields, including politics, economics and eugenics. The text presents a personal perspective on evolution, produced in the hope of inducing 'some competent biologist to write a book suitable for the general reader in which recent changes of opinion in regard to organic evolution are clearly discussed and wisely criticised'. This book will be of value to anyone with an interest in the development of evolutionary theory.