127     Two or three states may alternate with one another. Thus, for instance, in the case of double alternating diseases, certain pains may occur persistently in the legs, etc., immediately on the disappearance of a kind of ophthalmia, which latter again appears as soon as the pain in the limbs has gone off for the time—convulsions and spasms may alternate immediately with any other affection of the body or some part of it—in a case of threefold alternating states in a common indisposition, periods of apparent increase of health and unusual exaltation of the corporeal and mental powers (extravagant gaiety, extraordinary activity of the body, excess of comfortable feeling, inordinate appetite, etc.) may occur, after which, and quite unexpectedly, gloomy, melancholy humor, intolerable hypochondriacal derangement of the disposition, with disorder of several of the vital operations, the digestion, sleep, etc., appear, which again, and just as suddenly, give place to the habitual moderate ill-health; and so also several and very various alternating states. When the new state makes its appearance, there is often no perceptible trace of the former one. In other cases only slight traces of the former alternating state remain when the new one occurs; few of the symptoms of the first state remain on the appearance and during the continuance of the second. Sometimes the morbid alternating states are quite of opposite natures, as for instance, melancholy periodically alternating with gay insanity or frenzy.