Darwin on Man (1974) is an annotated edition of Charles Darwin's early notebooks, edited by Paul Barrett with an introduction by Howard Gruber. These notebooks, known as the "M and N notebooks," contain Darwin’s reflections from when he first formulated the theory of natural selection. Gruber's introduction, A Psychological Study of Scientific Creativity, argues that scientific breakthroughs are not sudden "eureka" moments, but the result of a long, gradual process involving hard work, imagination, and reasoning. The volume also reveals Darwin's philosophical and materialistic views, emphasizing his belief in the continuity between humans and animals and his rejection of a non-material soul. The notebooks show Darwin's deep engagement with literature, his methodical approach to scientific discovery, and his materialist view of consciousness, offering a new understanding of his intellectual evolution.