We must now go on to cases where the origin of the cleavage seems to us quite arbitrary, but where the cleavage itself seems even for that very reason to be more profound. It is no longer a question of some one morbidly exaggerated emotion, but rather of a scrap of the personality taken at random and developing apart from the rest. The commonest mode of origin for such secondary personalities is from some access of sleep-waking, which, instead of merging into sleep again, repeats and consolidates itself, until it acquires a chain of memories of its own, alternating with the primary chain.[13] And now, as an illustration of a secondary condition purely degenerative, I may first mention _post-epileptic_ states, although they belong too definitely to pathology for full discussion here. Post-epileptic conditions may run parallel to almost all the secondary phases which we have described. They may to all outward semblance closely resemble normality,--differing mainly by a lack of rational _purpose_, and perhaps by a recurrence to the habits and ideas of some earlier moment in the patient's history. Such a condition resembles some hypnotic trances, and some factitious personalities as developed by automatic writing. Or, again, the post-epileptic state may resemble a suddenly developed _idée fixe_ triumphing over all restraint, and may prompt to serious crime, abhorrent to the normal, but premeditated in the morbid state. There could not, in fact, be a better example of the unchecked rule of middle-level centres;--no longer secretly controlled, as in hypnotic trance, by the higher-level centres,--which centres in the epileptic are in a state not merely of psychological abeyance, but of physiological exhaustion.[14]