It is before all things useful to men to associate their ways of life, to bind themselves together with such bonds as they think most fitted to gather them all into unity, and generally to do whatsoever serves to strengthen friendship. But for this there is need of skill and watchfulness. For men are diverse (seeing that those who live under the guidance of reason are few), yet are they generally envious and more prone to revenge than to sympathy. No small force of character is therefore required to take everyone as he is, and to restrain one's self from imitating the emotions of others. But those who carp at mankind, and are more skilled in railing at vice than in instilling virtue, and who break rather than strengthen men's dispositions, are hurtful both to themselves and others.