happiness
Note in what follows (see especially para219) that both happiness and strength are relative qualities which depend on our abilities to satisfy our own needs. If desires and strengths are in equilibrium (i.e. if we are able to satisfy our desires through our own efforts) we are happy; if our desires surpass our ability to satisfy them we are miserable. Since young children are relatively weak, the challenge is to limit their desires to ones that can be easily satisfied.