Why can't a person entirely possess all the characteristics of good?

When it comes to beasts, two models exist: the lion, which represents brute force and strength, and the fox, which represents wiliness. A prince needs both, for one without the other will lead only to ruin. Machiavelli, as might be expected, proceeds to focus on the fox: “a prudent prince cannot and should not keep his word when to do so would go against his interest.” To be crafty and to be able to deceive, the mythical hallmarks of the fox, are key skills for any ruler. You can break promises and treaties as long as you can hide your duplicity; you must therefore be “a great liar and hypocrite.”