Any man who tries to be good all the time is bound to come to ruin among the great number who are not good. Hence a prince who wants to keep his authority must learn how not to be good, and use that knowledge, or refrain from using it, as necessity requires. Meanwhile, men ought either to be well treated or crushed, because they can avenge themselves of lighter injuries, of more serious ones they cannot. The injury ought to be of such a kind that one does not stand in fear of revenge.