First published in 1974 as a companion volume to Darwin on Man by Howard E. Gruber, Paul Barrett's transcriptions of Darwin's M and N notebooks served to shed new light on the evolutionist's methods and motivation. According to Stephen Jay Gould in the New York Times Book Review, "Darwin kept [these notebooks] primarily in 1838, when he was 29 years old. In them, he recorded his early conviction of evolutionary continuity between humans and all other animals. . . . These notebooks display all the features of humanistic intellect that his detractors denied. We find erudition in his comments on Plato, Locke, Hume, Adam Smith, Whewell, Burke, Montaigne, Lessing and Spencer. . . . We appreciate an artistic bent in his delight with nature and her prophet Wordsworth. . . . We grasp the breadth of his bold attempt to clothe all human thought and behaviour in a new evolutionary garb. . . . Charles Darwin was reconstructing the world and he knew exactly what he was doing."