A well-known classification is that of Charcot, who supposes three stages - the cataleptic, lethargic, and somnambulic. I shall go into more details as to these later, but will remark here that this classification has no universal value. Pitres partly follows Charcot, but accepts so many different kinds of hypnotic states that a general view is thereby rendered only more difficult. The classification made by Gurney - alert and deep stages - is only accurate for a few cases. In the same way the three stages supposed by Richet, Fontan, and Segard are not sufficiently well defined for practical use. According to Delbceuf, there are two stages in hypnosis, one with and the other without analgesia. As, however, complete insensibility to pain is very rare, and as the transitions are vague, insensibility to pain does not seem to me to be a suitable distinguishing characteristic. The classifications made by Liebeault, Bernheim, and Forel are well known. As they agree in the main, only differing in the number of stages - according to Liebeault, 6; according to Bernheim, 9; according to Forel, 3, - I shall only cite that of Forel: -

Stage 1. Drowsiness: the patient can resist suggestions only with great effort.

Stage 2. Hypotaxy ("charme"): the eyes are fast closed and cannot be opened; the subject is obliged to obey various suggestions.

Stage 3. Somnambulism: it is characterized by a loss of memory on waking, and also by post-hypnotic phenomena.

The classifications of Liebeault, Forel, and Bernheim rest chiefly on loss of memory, as a particular group (Forel's 3rd stage) of hypnotic states with loss of memory is placed in contrast with the others (Forel's 1st and 2nd stages), in which no amnesia exists.

Those hypnotic states in which loss of memory exists are called somnambulism by the authors above named. Wienholt also has already said that the magnetic states with ensuing loss of memory may be called somnambulism.

It would be better, however, not to make our .estimate of the stages of hypnosis dependent on loss of memory, but on the phenomena which appear during the hypnosis itself. Memory after hypnosis is dependent on many other factors which have nothing to do with the depth of the hypnosis. A chance view of any external object will suffice to arouse a whole chain of mental images implanted in the memory; further, we shall see that memory is influenced by suggestion. Delboeuf, who often experimented with profound hypnoses, declares that the subjects after the awakening were able to give an account of all the hypnotic incidents. I should consequently prefer to judge of the depth of the hypnosis only from the phenomena of the hypnosis itself.

The numerous subdivisions given by Lidbeault and Bernheim are not easy to utilize, because there exists no uniform principle for such classification. For example, one stage is distinguished by the complete closing of the eyes, and a deeper stage by motor disturbances in the arms. As these last, however, can also occur when the eyes are open, they cannot be regarded as a sign of the deepening of the stage in which the eyes are closed; for in the deepening all the phenomena of the previous and lighter stages must appear (Max Dessoir).

In order to avoid these difficulties, Max Dessoir has published a classification of the stages of hypnosis which is as simple as it is comprehensive and clear, and which I still consider to be the best, just as I did many years ago. According to this the states fall into two large groups, which are divided from each other by the extent of the functional disturbances. In the first group merely the voluntary movements show changes; in the second group abnormalities in the functions of the sense organs are added. The principle of this classification was already known to Kluge. If we accept Dessoir's classification, the minority of subjects belong to Group II.; thus, assuming 75 per cent. to be susceptible, 55 per cent. belong to Group I. and 20 per cent to Group II. According to Kron this latter percentage is perhaps too high. He conjectures that through practice and other factors these figures might vary considerably. The results which Vogt has obtained are simply marvellous - 99 cases of somnambulism in 119 subjects experimented on.

It will be understood that in Dessoir's two groups many stages and types can be distinguished. For example, we see that many a hypnotic state belonging to Group I. is merely characterized by the closing of the eyes, which the subject cannot voluntarily open, as in the first experiment (p. 34). This state used to be considered as a particular stage of hypnosis, but according to the explanation given above it takes its place as merely a particular form of Group I. It was frequently represented as a particular stage of hypnosis, because in many cases hypnosis is ushered in by a closing of the eyes, while other muscles are only affected later on. However, this may be a pure accident (Max Dessoir); we have accustomed ourselves more and more to induce hypnosis by affecting the eyes, and to provoke a closing of them as quickly as possible; but this is nothing but a habit, resulting from the identification of hypnosis with sleep. Hypnotists exist who induce hypnosis when the eyes are wide open, as is the case in "fascination," which will be discussed later (cf 3rd experiment, p. 35). Lcewenfeld, also, has elaborated a method in which any effect on the eyes is only of secondary importance.

I myself have met many people in whom it was impossible to bring about any abnormality in the movements of the eye, while other muscles were easily affected. For this reason, I think the assertion of Michael that hypnosis can only be proved when the eyes are completely closed is entirely mistaken. Certainly he is perfectly right when he says that we should not ascribe to hypnosis the states of fatigue and giddiness which ensue after long attention, unless other phenomena typical of hypnosis also appear.

It is clear that the two groups cannot be sharply divided from one another. Also the transition from a normal state to hypnosis is gradual, and certainly not so sudden as some think. We find many stages even before we arrive at the closing of the eyes, which certainly does not indicate a deep hypnosis; at first only heaviness of the eyelids, then a desire to close the eyes, then a difficulty in opening them, and finally their complete closure. All possible stages are displayed. Further, a deep hypnosis is not always attained at once; the light states are often passed through before the deepest appears. It is naturally difficult, through all these different transitions, to decide the exact moment of the appearance of hypnosis. A deep sigh, which often ushers in the beginning of hypnosis, is by many wrongly considered as diagnostic of the moment, particularly as this symptom is easily spread by imitation (Delboeuf). The movements of swallowing which appear, especially after long fixation, have equally little significance.

As already shown, the word "hypnosis " is derived from the Greek and this might induce one to conclude that the term hypnosis should only be used to describe a condition resembling sleep. In reality, however, the cases in the first group show no resemblance to sleep or a loss of consciousness. And yet there is a very prevalent notion amongst laymen that there can be no hypnosis without sleep and loss of consciousness, and persons holding this view do not refer the conditions exhibited by the first group to hypnosis. But this is not a question of what the layman thinks or believes; as Vogt has rightly pointed out what may or may not be ascribed to hypnosis can only be decided by those persons who have devoted themselves to a critical study of the whole subject. To prevent any confusion which might possibly arrise from the etymological resemblance of the words "hypnos" and "hypnosis," it has been proposed to distinguish those cases in which there is no semblance of sleep and in which consciousness remains normal, from deep hypnosis, by a distinct appellation.