Many other attempts have been made to define suggestion, but in some instances theory and definition have been confused. To a certain extent this objection applies to those definitions in which the associative disposition is held to be the chief characteristic of suggestion. The definitions given by Schrenck-Notzing, Schaffer, Lcewenfeld, and Wundt belong to this category, although they contain much that is valuable from a theoretical point of view. There are also other definitions which do not differ very much from that laid down by Lipps. For example, Hirschlaff considers the production of an effect without a tangible cause to be the most important point in suggestion. He lays stress on the absence of motive, while others, like Dubois, consider that the effects of suggestion are produced in a somewhat mysterious manner. Vogt holds suggestion to be the abnormally powerful action of the desire to attain an end. I myself believe that the definition I have given will suffice to carry us through our further investigations.

We shall now see that suggestion plays an extraordinarily great part in hypnosis, and it may be remembered I have already given numerous instances of suggestion in cases I have referred to. The Nancy method of inducing hypnosis is of a similar nature; an effort is made to induce the patient to believe that he is going to be hypnotized, and when the effort is successful hypnosis follows.

Now, there are cases in which the notion of an effect may apparently arise spontaneously, without the intervention of a second person, and the effect itself be produced, even when the subject is unwilling. We often meet with this in disease. I have already mentioned the case of a man blushing because he was firmly convinced that he was blushing. But there are cases in which people blush without anybody interfering with them. The notion of blushing is to a certain extent personal, and is called by pathologists the "fear of blushing." Fear and imagination here run hand in hand. As soon as such a person imagines that he or she may blush, then he or she blushes. Here the idea of blushing is not aroused by a second party; it is purely personal, and we therefore term it a case of autosuggestion in contradistinction to a notion aroused by some other person, which Bentivegni calls external or hetero-suggestion. Auto-suggestion of this nature plays an important part in certain pathological conditions. There are many stammerers who only stammer when they think they are going to stammer, but who can speak quite well when they do not think about stammering. Many an impulsive idea may be ascribed to auto-suggestion, although Lipps attempts to draw a distinction between the two.

For example, a patient suffering from agoraphobia is filled with the fear that he cannot cross an open space alone. No reasoning is of avail here; the patient acknowledges its justice without permitting it to influence him. Often - but not always - logic is for the most part powerless over these auto-suggestions. Many hysterical paralyses are also auto-suggestions; the patient cannot move his legs because he is convinced that movement is impossible. If this conviction can be shaken, movement is at once practicable.

Auto-suggestion may be called up by some external cause. Charcot referred some isolated traumatic paralyses to something of this kind. According to this view, a violent blow on the arm, with its resultant disturbances of sensibility, may produce in the person concerned a conviction that he cannot move his arm. As the conviction was called up by the blow, this case stands somewhere between external suggestion and auto-suggestion. We will call all cases in which the autosuggestion did not arise spontaneously, but was the secondary result of something else, such as a blow, indirect suggestions, as opposed to direct suggestion, which arouses a certain idea immediately, of which I have already given several examples. It is not always necessary that there should be a conscious mental act in suggestion; individuality and habit sometimes replace this, and play a great part in the training of the subject, of which we have still to speak. If some external sign, such as a blow on the arm, has several times, by means of a conscious mental act, produced the auto-suggestion that the arm is paralyzed, then the auto-suggestion may repeat itself later mechanically at every blow without any conscious thought of the effect of the blow.

A particular psychical state, disposing to suggestion, is a necessary condition of its appearance. The disposition to suggestion is called "suggestibility."

We shall now see that we can in this way obtain many effects by employing suggestion during hypnosis. We shall also see that we can produce these effects not only during hypnosis (hypnotic or intra-hypnotic suggestion), but that they extend to the time following hypnosis. This is post-hypnotic suggestion. By means of this we can tell the person in the hypnotic state that after his awakening a particular result will follow. We can also distinguish another kind of suggestion: something may be suggested to the subject before the hypnosis which is to follow in that state. This is pre-hypnotic suggestion (Maack, Stembo).