Book 1.21
Vengeance effects two purposes: it either affords compensation to the person to whom the wrong was done, or it ensures him against molestation for the future. A prince is too rich to need compensation, and his power is too evident for him to require to gain a reputation for power by causing anyone to suffer. I mean, when he is attacked and injured by his inferiors, for if he sees those who once were his equals in a position of inferiority to himself he is sufficiently avenged. A king may be killed by a slave, or a serpent, or an arrow: but no one can be saved except by someone who is greater than him whom he saves. He, therefore, who has the power of giving and of taking away life ought to use such a great gift of heaven in a spirited manner. Above all, if he once obtains this power over those who he knows were once on a level with himself, he has completed his revenge, and done all that he need to towards the punishment of his adversary: for he who owes his life to another must have lost it, and he who has been cast down from on high and lies at his enemy's feet with his kingdom and his life depending upon the pleasure of another, adds to the glory of his preserver if he be allowed to live, and increases his reputation much more by remaining unhurt than if he were put out of the way. In the former case he remains as an everlasting testimony to the valour of his conqueror; whereas if led in the procession of a triumph he would have soon passed out of sight. If, however, his kingdom also may be safely left in his hands and he himself replaced upon the throne from which he has fallen, such a measure confers an immense increase of luster on him who scorned to take anything from a conquered king beyond the glory of having conquered him. To do this is to triumph even over one's own victory, and to declare that one has found nothing among the vanquished which it was worth the victor's while to take. As for his countrymen, strangers, and persons of mean condition, he ought to treat them with all the less severity because it costs so much less to overcome them. Some you would be glad to spare, against some you would disdain to assert your rights, and would forbear to touch them as you would to touch little insects which defile your hands when you crush them: but in the case of men upon whom all eyes are fixed, whether they be spared or condemned, you should seize the opportunity of making your clemency widely known.