CHAPTER XX PSYCHOTHERAPY While many forms of mental disease have a physical origin in the brain, nervous system, and state of the blood, many others are purely mental from beginning to end, although the body may be chosen as the scene of some of their manifestations. Modern medicine is learning to deal with mental diseases by mental methods, and of these the principal types may be of interest. It must be remembered, however, that psychotherapy is the youngest of the sciences, and is still in its experimental stage; and that though magnificent work has been done by the pioneers, they cannot claim to have said the last word upon the structure of the human mind, for even if they knew all that was to be known, leaving nothing to be discovered by future investigation, which they would be the last to claim on their own behalf, though their disciples are not always blessed with the same modesty of genius, evolution is moving on, with the human mind at its apex, so that statements which were true of human nature before the Great War may have to be modified and supplemented when the Great Peace becomes an established fact. Our knowledge of the mind, its diseases and therapy, is far from complete. The investigation of each human mind is in the nature of a voyage of discovery; though the coastline of the mental landscape may be known to us, the hinterland is unmapped. We do not know what lies behind the human personality; we are equally ignorant of the exact nature of its relations with its environment, and while our knowledge is in this state we cannot speak upon any point with finality. CHAPTER XXI PSYCHOANALYSIS The foundations of this method and theory were laid by Sigmund Freud of Vienna, and set forth by him in his epoch-making book, the _Interpretation of Dreams_, published in 1900. Two schools of psychoanalysis exist at the present time: the Vienna school, which adheres strictly to the doctrines of Freud; and the Zurich school, which subscribes to a modification of these doctrines as taught by Dr. Jung. While both schools agree upon general principles as to the anatomy of the mind, they differ in their teaching as to the _modus operandi_ of mental disease. Freud holds that functional nervous disorders are due to the retention by the subconscious mind of an infantile attitude towards life, and especially towards sex, and that this attitude, which should have been outgrown and left behind, sets up stresses and strains in the mind which lead to the manifestations of mental disease. He gives us the concept of the accumulation of emotion in this wound in the mind, just as pus accumulates in an abscess, giving rise to tenderness and pain. He conceives the function of the psychoanalyst to be to lance this abscess by bringing the subject of distress into consciousness, whereby the repressed emotion is realised and fully experienced, and thereby got rid of. This process is technically known as ABREACTION.