Now here a new kind of difficulty has to be added to those which we have already found in attempting to formulate Common Sense. For we find some who say that, as it is essential to Friendship that the mutual kindly feeling, and the services springing from it, should be spontaneous and unforced, neither the one nor the other should be imposed as a duty; and, in short, that this department of life should be fenced from the intrusion of moral precepts, and left to the free play of natural instinct. And this doctrine all would perhaps admit to a certain extent: as, indeed, we have accepted it with regard to all the deeper flow and finer expression of feeling even in the domestic relations: for it seemed pedantic and futile to prescribe rules for this, or even (though we naturally admire and praise any not ungraceful exhibition of intense and genuine affection) to delineate an ideal of excellence for all to aim at. Still, there seemed to be an important sphere of strict duty--however hard to define--in the relations of children to parents, etc., and even in the case of friendship it seems contrary to common sense to recognise no such sphere; as it not unfrequently occurs to us to judge that one friend has behaved wrongly to another, and to speak as if there were a clearly cognisable code of behaviour in such relations. Perhaps, however, we may say that all clear cases of wrong conduct towards friends come under the general formula of breach of understanding. Friends not unfrequently make definite promises of service, but we need not consider these, as their violation is prohibited by a different and clearer moral rule. But further, as all love is understood to include[202] a desire for the happiness of its object, the profession of friendship seems to bind one to seek this happiness to an extent proportionate to such profession. Now common benevolence (cf. _ante_, § 5) prescribes at least that we should render to other men such services as we can render without any sacrifice, or with a sacrifice so trifling as to be quite out of proportion to the service rendered. And since the profession of friendship--though the term is used to include affections of various degree--must imply a greater interest in one’s friend’s happiness than in that of men in general, it must announce a willingness to make more or less considerable sacrifices for him, if occasion offers. If then we decline to make such sacrifices, we do wrong by failing to fulfil natural and legitimate expectations. So far there seems no source of difficulty except the indefiniteness inevitably arising from the wide range of meanings covered by the term Friendship. But further questions arise in consequence of the changes of feeling to which human nature is liable: first, whether it is our duty to resist such changes as much as we can; and secondly, whether if this effort fails, and love diminishes or departs, we ought still to maintain a disposition to render services