It is easy to understand how this state of things gradually became transformed into the considerably different position of parents and child we have known, which doubtless attained its climax nearly a century ago.  Feudal conditions, with the large households so well adapted to act as seminaries for youth, began to decay, and as education in such seminaries must have led to frequent mischances both for youths and maidens who enjoyed the opportunities of education there, the regret for their disappearance may often have been tempered for parents.  Schools, colleges, and universities began to spring up and develop for one sex, while for the other home life grew more intimate, and domestic ties closer.  Montaigne’s warning against the undue tenderness of a narrow family life no longer seemed reasonable, and the family became more self-centred and more enclosed.  Beneath this, and more profoundly influential, there was a general softening in social respects, and a greater expansiveness of affectional relationships, in reality or in seeming, within the home, compensating, it may be, the more diffused social feeling within a group which characterised the previous period.

So was cultivated that undue tenderness, deplored by Montaigne, which we now regard as almost normal in family life, and solemnly label, if we happen to be psycho-analysts, the Oedipus-complex or the Electra-complex.  Sexual love is closely related to parental love; the tender emotion, which is an intimate part of parental love, is also an intimate part of sexual love, and two emotions which are each closely related to a third emotion cannot fail to become often closely associated to each other.  With a little thought we might guess beforehand, even while still in complete ignorance of the matter, that there could not fail to be frequently a sexual tinge in the affection of a father for his daughter, of a mother for her son, of a son for his mother, or a daughter for her father.  Needless to say, that does not mean that there is present any physical desire of sex in the narrow sense; that would be a perversity, and a rare perversity.  We are here on another plane than that of crude physical desire, and are moving within the sphere of the emotions.  But such emotions are often strong, and all the stronger because conscious of their own absolute rectitude and often masked under the shape of Duty.  Yet when prolonged beyond the age of childhood they tend to become a clog on development, and a hindrance to a wholesome life.  The child who cherishes such emotion is likely to suffer infantile arrest of development, and the parent who is so selfish as to continue to expend such tenderness on a child who has passed the age of childhood, or to demand it, is guilty of a serious offence against that child.