Passage four
There are two methods of fighting, the one by law, the other by force; the first method is that of men, the second of beasts; but as the first method is often insufficient, one must have recourse to the second. It is, therefore, necessary for a prince to know how to use both the beast and the man. This was covertly taught to the rulers by ancient writers, who related how Achilles and many other ancient princes were given Chiron the centaur to be brought up and educated under his discipline. The parable of this semi-animal, semi-human teacher is meant to indicate that a prince must know how to use both natures and that without one the other is not durable.
A prince, being thus obliged to know well how to act as a beast, must imitate the fox, and the lion, for the lion cannot protect himself from traps and the fox cannot defend himself from wolves. Those that wish to be only lions do not understand this. Therefore, a prudent ruler ought not to keep faith when by doing so it would be against his interest, and the reasons which bind himself no longer exist. If men were all good, this precept would not be a good one; but as they are bad, and would not observe their faith with you, so you are not bound to keep faith with them. Nor have legitimate grounds ever failed a prince who wishes to show colorable excuse for the nonfulfilment of his promise. Of this one could furnish an infinite number of examples, and show how many times peace has been broken, and how many promises rendered worthless, by the faithlessness of princes, and those that have best been able to imitate the fox have succeeded best. But it is necessary to be able to disguise this character well, and to be a great feigner and dissembler, and men are so simple and so ready to obey present necessities, that the one who deceives will always find those who allow themselves to be deceived.

The writer suggests that a successful leader must _____________.