The most important of all the organs: Darwin on the brain.

This article discusses Charles Darwin's interest in topics that may broadly be defined as 'neurological' in character. Using published and manuscript materials, it examines the sources of Darwin's knowledge of neurological matters and seeks to explain why questions concerning the relation of mind and brain both in humans and other animals were relevant to his wider concerns. The paper concludes with a discussion of Darwin's impact on late 19th and early 20th century neurological thought. The 150th anniversary of the publication of the Origin of Species and the 200th of the birth of its author afford an opportunity to reflect on Charles Darwin's relationship to neurology. The first section of this article considers the part played by what might broadly be defined as 'neurological' materials in the shaping of Darwin's theory. The following section provides a brief review of the impact that Darwin's ideas were to have upon subsequent neurological thought.