Since we know not how to endure an injury, let us take care not to receive one: we should live with the quietest and easiest-tempered persons, not with anxious or with sullen ones: for our own habits are copied from those with whom we associate, and just as some bodily diseases are communicated by touch, so also the mind transfers its vices to its neighbours. A drunkard leads even those who reproach him to grow fond of wine: profligate society will, if permitted, impair the morals even of robust-minded men: avarice infects those nearest it with its poison. Virtues do the same thing in the opposite direction, and improve all those with whom they are brought in contact: it is as good for one of unsettled principles to associate with better men than himself as for an invalid to live in a warm country with a healthy climate. You will understand how much may be effected this way, if you observe how even wild beasts grow tame by dwelling among us, and how no animal, however ferocious, continues to be wild, if it has long been accustomed to human companionship: all its savageness becomes softened, and amid peaceful scenes is gradually forgotten.