182. To speak of strife first, which cannot easily be wholly prevented among children, and which is present to their minds, at least as a possibility, self-help against unexpected bodily assaults cannot be forbidden. A determined self-defence is rather to be recommended, but self-defence paired with a merciful treatment of one’s assailant. On the other hand, it is necessary to prohibit absolutely any arbitrary appropriation of objects, even though these objects should consist of ownerless or discarded trifles. No one must imagine that his mere pleasure is a law unto others. On the contrary, children ought to get used to limitations on ownership. That which has been given them for a certain purpose is to be used for that purpose alone, and must be taken care of with that purpose in view. Promises among children should not lightly be declared void, however foolish and impossible of fulfilment. The boy who, by a hasty promise, puts himself in an embarrassing position must be made conscious of the fact. Let his perplexity serve as a warning for the future. But over-hasty promises are to be accepted as little as they are to be made; and here is where we have to begin in untying the knots in which children occasionally entangle themselves. It is not undesirable that pupils by their own acts furnish themselves with a few keenly-felt instances of complicated questions of rights. But pleasure in wrangling must be discountenanced; the pupils should learn to prevent and to avoid contention. They may gain enough familiarity with it to realize that it gives displeasure. 183. At this point two paths open to our reflection. In the first place, contention pleases children because it implies strength; in seeking it they are, as a rule, merely giving vent to excess of animal spirits. The outlet in this direction we must block, but we must furnish another elsewhere. Gymnastic exercises, too, are exhibitions of strength; emulation, which is not contention, is a welcome feature of sport and play. Mental activity likewise affords suitable opportunities for excelling; it also provides proper occasions for making comparisons; but relative excellence, children must understand distinctly, is not to be advanced by them as a basis for claims. Where the question is one of degree of attainment,--therefore one of _perfice te_,--the pupil is supplied with a practically useful standard by his own progress and retrogression. To hold up one pupil as a model for another to follow awakens envy; it will be much better, instead, to make allowances where a weak pupil cannot do more than he is actually doing.