Klein posited that a healthy development implies that the infant has to split its external world, its objects and itself into two categories: "good" (i.e., gratifying, loved, loving) and "bad" (i.e. frustrating, hated, persecutory). This splitting makes it possible to introject and identify with the good. In other words: splitting in this stage is useful because it protects the good from being destroyed by the bad. Later, when the ego has developed sufficiently, the bad can be integrated, and ambivalence and conflict can be tolerated.