Teachers are relatively powerless because they have little to offer that their pupils urgently want. By the same token, even headmasters have power over their staff only within quite circumscribed limits: they have few gifts to offer, apart from approval and perhaps occasional unmerited promotions, with which to place their subordinates under obligation. It is chiefly through their (limited) power, not to apply rules, but to suspend them, that teachers have power over pupils and headmasters over teachers. The power of schools over pupils is probably related to the 'price' they exact from them. If the price they demand of pupils is high, in terms of rigorous entrance standards and relentless effort and even hardship once they are in, schools may have considerable power to modify pupils' behaviour, perhaps especially after they have left. When they have given so much throughout their schooldays, Old Boys will seldom admit that it was not really worth it: in retrospect the experiences of schooldays will acquire a remarkable potency. Guardsmen like Etonians are created in the ten years after their discharge. The power of schools may be long delayed, operating through a process of retroactive socialization.