Of course, unselfish people who are lacking in emotional control, or carry about with them the unassimilated memory of childhood emotional shocks, may likewise become nervous invalids of one sort or another. But they are much less likely to do this than selfish people are, if only because the unselfish are not so eternally occupied with themselves. They have externalised their thoughts; they have neither time nor inclination to think about trivial aches and pains. Unless overwhelmed by an unexpected emotional shock--for instance, by the sudden death of a beloved relative or by the shock of some great fright--they are likely to go through life comfortably and normally enough. On the other hand, the selfish person is always in danger of becoming morbidly introspective, with resultant damage to the functioning of his nervous system. Besides all this, there is the important consideration that to be selfish means to be unhappy. Even if actual nervous ailments of a serious sort are escaped by the selfish, unhappiness in the social relations and in the _family_ relations is certain to be experienced. It is my firm belief that, more than any other single cause, selfishness is responsible for misunderstandings and increasing bitterness between husband and wife, ending all too often in a breakdown of the sacred institution of marriage. To deal successfully with that dread problem of to-day--the divorce evil--we must, I submit, first appreciate how basic in marriage failure is the factor of selfishness. To this theme I now invite the attention of my parent-readers, for it is a theme of particular interest to them. If I am correct, it is through education for marriage and, most of all, through education against selfishness that the divorce problem can most surely he solved. What a problem it is! And a problem that has been steadily growing in seriousness. In the twenty years from 1867 to 1886, according to figures compiled by the United States Census Bureau, 328,716 divorces were granted throughout the country. In the next twenty years--that is, from 1887 to 1906--divorces aggregated the enormous total of 945,625. In other words, in a period of only twenty years nearly two million men and women in the United States had their marriage ties legally severed, the break-up being at the rate of about one hundred and thirty divorces a day. And this increase has been progressively growing year after year. In 1867 there were only 9,937 divorces for the entire country. In 1906 no fewer than 72,012 divorces were granted. Four years ago an unofficial estimate put the annual divorce crop at nearly one hundred thousand, or, roughly, one hundred divorces for every one hundred thousand of population. The same estimate indicated that one marriage in every twelve ends in divorce.