If I may judge from the nature of the welcome extended to the Abstract, some readers may be disappointed to find that so large a part of the complete treatise is devoted to uncivilized peoples. I too have a greater personal interest in the ideas and behaviour of civilized societies; and, if I had been concerned with the mere proving of a thesis (in the sense in which the word is understood by those who adopt comparative methods), I should probably have dismissed uncivilized societies with the eclectic summary that is usually given to them, and confined my serious discussion to some highly selected historical data. But I have not tried to prove a thesis, and have none to prove; I have merely conducted an inquiry; and in such a case the importance attached to any society, civilized or uncivilized, must be in proportion to our knowledge of it. I wish to emphasize this. When I started these researches I sought to establish nothing, and had no idea of what the result would be. With care-free open-mindedness I decided to test, by a reference to human records, a somewhat startling conjecture that had been made by the analytical psychologists. This suggestion was that if the social regulations forbid direct satisfaction of the sexual impulses the emotional conflict is expressed in another way, and that what we call 'civilization' has always been built up by compulsory sacrifices in the gratification of innate desires. The psychologists arrived at this conclusion after inquiring into the nature and causes of mental disturbances; they made no attempt to fortify it by a reference to cultural data; so I decided to investigate the matter. I began in all innocence; had I realized how greatly, as the result of my work, I should have to revise my personal philosophy, I might even have hesitated to begin at all; I was so far from desiring to illustrate a personal conviction that I always struggled against arriving at the conclusions which the evidence appeared to force upon me; and I continued to work, resisting every temptation to speak, until I was satisfied that I could find no exception to the apparent rules. I then collected so much of my material as seemed necessary and advisable. This treatise is the result.