John Maynard Smith was originally trained as an engineer but, despite important excursions into animal mechanics, ecology and ethology, he is now best known as an international authority on evolution. His pre-eminence is based in large part on original research contributions coupled with an uncanny ability for revealing simple explanations to apparently intractable problems. This wide-ranging volume contains a collection of new and original essays, all inspired by Maynard Smith's writings. The essays span the whole field of evolutionary biology: from microevolution to macroevolution; from evolutionarily stable strategies to sympatric speciation; and from population processes in plants to the arithmetic of assessment in animals.