The next great change is being made now; it concerns a further development of mind and a consequent fresh mode of connection of sex with mental life. As we have outlined above, this change in mind consists in the tendency towards uniting the different parts of the psyche, both those portions given by heredity and the modification due to experience, into a single organic whole, and in making this whole more dominant over the other aspects of the organism; the consequent tendency as regards the relationship of sex to the organism is towards taking it out of its single groove, its water-tight compartment, and bringing it into more complete and more permanent union with the rest of the mind. Furthermore, the main change and the consequent change as regards sex are both of a biologically progressive nature. 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.