Cerebral localization, including hierarchical organization of the nervous system, was the critical conceptual advance that made possible the development of modern neuroscience in the nineteenth century. Some of our most basic ideas about neural organization were contributed by Hughlings Jackson. In the early twentieth century, Charles Sherrington combined localization with the neurone theory to create the paradigm of neurophysiological integration. Because Sherrington was educated in the Jacksonian tradition of British neurology, Sherringtonian integration contains ideas that are derived from Jackson and from Herbert Spencer.