Geology, zoology, sociology, and comparative psychology, all show us the evolution of that which is simple into that which is complex, from the cave man, with his few needs and problems, to the complications of a modern industrial society. And we see in the little segment of the evolutionary arc with which we are most closely concerned that the chief factor is the herd instinct which is pressing us all the time towards a more complete socialisation of humanity, and that any adaptation which an individual makes must be in relation to his integration as a social unit and not to his needs as a solitary individual. Diagnostic and descriptive psychology must be distinguished from remedial psychology of which we have had all too little. Research on the abnormal mind alone will not give us the key to a healthy life, we must study social psychology as well as individual psychology, because man is a social animal, and his mental processes are determined by this fact; any adaptation he makes, and adaptation is the basis of psychotherapy, must be in relation to his social group as well as to his own subconscious wishes; it is not enough to bring these wishes into the light of consciousness, they must be synthesised with the rest of the personality, to the social organisation of which that personality is a unit, and to the great evolutionary drift of which even the race itself is but a partial expression. Psychotherapy may begin with the primitive, but it must end with the divine, for both are integral factors in the human mind. TRANSCRIBER’S NOTES Spelling and grammatical errors on page 81 (Chapter XXI) have been left unchanged.