We are now, I think, owing to our taking this broad biological view, in a better position to make up our minds as to some at least of the difficulties which beset us to-day in any attempt to deal squarely with the relation of sex to human life. It is true that some of these difficulties are permanent. The synthesis of a unitary and comprehensive mental organization can never be an easy task. The child is endowed with a number of instinctive tendencies which, as in animals, each tend whenever aroused to occupy the whole mental field to the exclusion of all others, producing divergence and lack of co-ordination instead of unity and organization. Then again, the experience of any one individual may be highly unusual. For the child to co-ordinate his various tendencies with each other and with his own experience and with the tradition and experience of the race must always be difficult, and there will always be some failures.
There is another permanent difficulty, a biological disharmony, in the fact that sexual maturity in man comes several years before general maturity, and that again, at least in any state of civilization which we can at present imagine as practicable, several years before the economic possibility of marriage. There will always be crises of adolescence; there will always be suffering and difficulty due to this disharmony in time between the origin of the full sexual instinct and the possibility of its proper satisfaction.
However, granted these permanent difficulties, there are others which may be reduced or made to disappear. Granted that we have to organize our minds into a whole, we can see the general plan on which we should aim at organizing it. We must aim first at having no barriers between different parts of the mind. Every attempt must be made in the education of children to prevent there being a stigma attached to one whole section of mental life, and so to avoid its partial or total dissociation from the rest. On the other hand, the absence of barriers does not imply the absence of any relation of subordination or dominance of one part to another. One of the most important biological generalizations is that progressive evolution is accompanied by the rise of one part to dominance and, whenever there are many parts to be considered, by the arrangement of the rest in some form of hierarchy, each part being subordinate to one above, dominant to one below. It is such a hierarchy which we must try to construct in our mental organization.