[Sidenote: Modification of conduct as the result of Conflict] This open and unrestricted expression of primitive tendencies is, however, confined to a phase of relatively short duration in the history of the child's mind, being generally found only in the first few years of life. The crude love or hate for mother or father, brother or sister, which we have so far been considering, does not long persist in its original form; the normal development of the mind requires that these primitive emotional attitudes shall undergo grave and far reaching modifications, the production of which constitutes an important step towards the attainment of the adolescent or adult point of view. [Sidenote: The forces of Repression] [Sidenote: Sexual inhibition] These modifications are the result of a conflict which takes place in the mind between the love and hate impulses in their original form and certain tendencies of an antagonistic nature which (as already indicated in the last chapter), make their appearance after a certain time and threaten to inhibit the cruder manifestations of the primitive impulses. These new tendencies are themselves, in all probability, derived from more than one source. Those which produce modification in the love impulses of the child, may be regarded as constituting, no doubt, only so many particular instances of that inhibition of sexual and quasi-sexual activity which exercises such a large influence in the formation of human character in general. [Sidenote: Herd Instinct]