Everyone understands how praiseworthy it is for a prince to remain true to his word and to live with complete integrity without any scheming. However, weve seen through experience how many princes in our time have achieved great things who have little cared about keeping their word and have shrewdly known the skill of tricking the minds of men; these princes have overcome those whose actions were founded on honesty and integrity. It should be understood that there are two types of fighting: one with laws and the other with force. The first is most suitable for men, the second is most suitable for beasts, but it often happens that the first is not enough, which requires that we take recourse to the second. Therefore, it is necessary for a prince to know how to act both as a man and as a beast. This was signified allegorically to princes by the ancient writers: they wrote that Achilles and many other ancient princes were given to be raised and tutored by the centaur Chiron, who took custody of them and disciplined them. This can only mean, this trainer who was half beast and half man, that a prince needs to know how to use either one or the other nature, and the one without the other will never last.

Website: http://www.wsu.edu/~dee/REN/PRINCE18.HTM