In fact, case work has convinced social workers that there are few things less permanent than desertion. In itself this provisional quality tends to create irritation in the minds of many of the profession. It is upsetting to plan for a deserted family which stops being deserted, so to speak, overnight. But in their understandable despair social workers sometimes overlook essential facts about the nature of marriage. The _permanence_ of family life is one of the foundation stones of their professional faith; yet they may fail to recognize certain manifestations of this permanence as part and parcel of the end for which they are striving. They would see no point in the practice adopted by a certain social agency which deals with many cases of family desertion. This society, when it has had occasion to print copies of a deserter's photograph to use in seeking to discover his present whereabouts, often presents his wife with an enlargement of the picture suitable for framing. The procedure displays, nevertheless, a profound insight not only into human nature but into the human institution called marriage. In the next chapter will be considered some of the causes that make men leave their homes. To deal effectively with the situation created by desertion, however, we have need of a wider knowledge than this. Not only what takes men away but what keeps them from going, what brings them back, what leads to their being forgiven and received into their homes again, are matters that seriously concern the social case worker. What is it that makes this plant called marriage so tough of fiber and so difficult to eradicate from even the most unfriendly soil? It is fortunate (since the majority of case workers are unmarried) that simply to have been a member of a family gives one some understanding of these questions. The theorist who maintains that marriage is purely economic, or that it is entirely a question of sex, has either never belonged to a real family or has forgotten some of the lessons he learned there.