The figure of J.H. Jackson is one of the most relevant in the history of neurology. His longest period not only during his training but also during his professional plenitude took place in the National Hospital. Jackson was a great clinician, wrote many articles and gave a lot of lectures, but never wrote either a treatise or a monograph about his special field. He did not carry out animal experiments. He introduced in Britain the use of the ophthalmoscope in the neurological exploration and founded the journal Brain. He was specially interested in language disorders, paralysis, vertigo, mental disorders, cerebral tumours and above all epilepsy. He systematized what we today know as complex partial crisis, establishing the link between the function of the temporal lobe and the sensorial auras, automatism's, déjà-vu and jamais vu phenomena. He described the uncinate crisis, the topographic progression of the motor partial crisis and its posterior generalisation, establishing the motor pattern of cerebral cortex. The clinical observations of epileptic phenomena, with the influence of the evolutive ideas from Spencer, were the seeds for the elaboration of the evolutive development of the function of the nervous system. His theory about evolution and dissolution of the neurological functions was the starting point for Freud's clinical investigation. The Jacksonian set of ideas were experimentally proved by the neurophysiological work of Sherrington.