It is impossible in a book of this nature to give a knowledge of the psychotherapeutic methods that can be of any practical use; the reader must refer to the many text-books upon the subject if such is desired. It must, however, be realised that the modern methods of dealing with the mind are extremely potent, and that it is possible to completely wreck a nature by their injudicious use. A knowledge, however, of the principles of mental hygiene can be nothing but beneficial, though the actual treatment of mental or nervous disease should be avoided by the amateur, for, whatever his theoretical knowledge, the practical experience of hospital and asylum work can alone give accuracy of diagnosis. The beginnings of certain forms of insanity are very hard to distinguish from nerve trouble, even by the expert, and the amateur who tries his prentice hand upon such a case by mistake is likely to have his error painfully and forcibly impressed upon his mind. Psychotherapy is the youngest of the sciences and in a state of vigorous and healthy growth, but there is as yet no orthodox body of doctrine which is regarded as being thoroughly established and accepted by all schools of thought. The lay reader, for whom this book is designed, would do well to be on his guard against dogmatic expressions of opinion which may be presented to him, either in lecture or in print, for our knowledge is not in a state to warrant them. We have learnt much, but we do not know all, and until we know much more than we do now, we must keep an open mind and judge tentatively. The popular vogue of applied psychology among those who are not in a position to form first-hand opinions makes this warning necessary. There is no “truth once and for all delivered” by a prophet on a mountain, but an earnest band of men and women adding stone by stone to the temple of human knowledge. The various methods of psychotherapy outlined here have each and all their value, but no one of them is a panacea for all the ills that flesh is heir to; the science is in its infancy, and the percentage of cure is by no means satisfactory. There is no standard of training for either medical men or lay analysts and owing to the great emphasis laid upon sex by the modern schools, the method is open to grave abuses in inexpert or unclean hands. CHAPTER XXIII THE PRACTICAL APPLICATION OF PSYCHOLOGY Those who have read the foregoing pages will see that there are certain broad divisions into which they fall. Let us now review these divisions in their relation to the practical art of living.