With less diagnostic elegance we sometimes reach the same end by taking careful records of pulse and breathing and involuntary movements during an apparently harmless conversation. The instruments at the disposal of the psychologist are those familiar to every psychological laboratory: the pneumograph, which registers the movements of respiration; the sphygmograph, which writes the pulsation of the artery in the wrist; the automatograph, or other instruments, which register the slight unintentional movements of the arm. If the examiner is skillful, he will not fail to discover the changes in breathing and pulse and reaction as soon as the painful groups of ideas are approached. More of theoretic interest and too cumbersome for practical diagnosis is the unfailing galvanic reaction from the skin in which the glands change their activity and their resistance to the galvanic current under the influence of hidden emotions. Yet all these methods, with exception of the last, are essentially useful only if the starting experience is still accessible to the memory of the patient. He may be unaware that it had anything to do with his nervous symptoms but he recognizes the experience still as soon as his attention is directed towards it. The psychologically more interesting but probably more exceptional situation is the one in which it is not only forgotten but cannot be recognized when it is brought to consciousness. The shortest way to get hold of such past impressions is the hypnotic one. The hypnotic state sharpens the memory and experiences of early childhood or apparently insignificant experiences of later life may be brought back when they would have been inaccessible to any intentional effort of the attention. Even still more surprising is the success if the association is left to a dreamy play of ideas suggested perhaps by gazing into a crystal ball or by a meaningless talking. Perhaps the patient lies with closed eyes on the couch while the physician holds his hand. A few words are given to him as a starting point and then he is thoughtlessly to pronounce whatever comes to his mind, not only unfinished sentences but loose phrases, single words, apparently without meaning and slowly ideas arise which betray the original intrusion. At last memories and lost emotions come again to the surface, and the watchful psychotherapist may discover the complex, which is then to be removed by discharge or by side-tracking. This is the so-called psychoanalytic method.