Peter Mark Roget: physician, scientist, systematist; his thesaurus and his impact on 19th-century neuroscience.

Peter Mark Roget (1779-1869) is best known for his Thesaurus, a project completed late in his long life. He trained as a physician, practiced medicine, and was interested in many branches of science. Much of his life was dedicated to the systematization of knowledge and identifying relationships. Although not an experimentalist in the modern sense of the word, he contributed to "neuroscience" in journal and encyclopaedia articles, as well as in books and lectures. He wrote extensively on comparative physiology, sensory systems, phrenology, optics, and various disorders affecting the nervous system. He viewed his two-volume Bridgewater Treatise of 1834 as his most significant achievement, turning to physiology and comparative anatomy to argue that God's existence can be seen in how living forms and their components are designed. Roget was active in many scholarly organizations, most notably the Royal Society of London, where he served for more than two decades as its secretary before "retiring" to pursue his Thesaurus.