The theories propounded by Charles Darwin in The Origin of Species have had a profound and revolutionary effect, not only on biology but also on philosophy, history, and theology. His concept of natural selection has created eruptive disputes among scientists and religious leaders of his time and ours. The phenomenal importance of his brilliant work is universally recognized, but the present volume marks the first scholarly attempt to compile a complete variorum edition of The Origin of Species, covering all of the extensive variants in the six texts published between 1859 and 1872. Darwin's changes were extensive. His book grew by a third as he rewrote many passages four or five times, and in this edition Morse Peckham has recorded every one of those changes. A book of such distinctive dimensions, on a subject of such profound importance, will be of intense interest to historians of biology, evolution, science, literature, and cultural development. It will be an invaluable aid to the clarification and full comprehension of this complex and renowned scientific classic.