The authors view an epileptic seizure as a series of symptoms which they can localize on the bases of data taken from stereoelectroencephalography literature. They reconstruct and compare the presumed organization (origin and propagation) of the discharge in 100 epileptic subjects. Both spontaneous and megimide-induced seizures are considered. The results involve 34 subjects with quite similar spontaneous and induced seizures. Comparison of the two critical modalities show that : 1) There is no variation in the chronological relationship of the symptoms. 3) There are differences in the symptomatology. These differences may be interpreted as non-uniform response of involved structures to the source of activation, or as involvement of new structures.