In Machiavelli's 'The Prince', Machiavelli points out many aspects on human nature. His view is that humans are evil and conniving. He is at an extreme, but not so far off. He believes that a leader must be evil and scheme in order to keep power. He also explains that in order to keep power, in any state of affairs, it is necessary that a leader can be immoral in order to preserve his status. A leader's immorality can extend to taking over a country to prove power to his own people, killing off families of leaders, or even breaking promises in order to gain what he needs to stay in power.
In Chapter 4, Machiavelli starts off with some ways a person can become a ruler. Machiavelli believes power is hereditary, because one who has never experienced it may be reckless with it. However, in cases of rebellion, Machiavelli is in favor of killing off the family of the ruler and suppressing the opposing party, which would be those in favor of the former leader:
And when fighting afterwards amongst themselves, each one was able to attach to himself his own parts of the country, according to the authority he had assumed there; and the family of the former lord being exterminated, none other than the Romans were acknowledged.
Machiavelli respects customs and religions of other 'kingdoms' but in his own way, his immorality for killing off families and suppressing opposing parties make for an immoral situation. In Chapter 5, Machiavelli proposes ways to keep control of countries which have had their own government, perhaps just overthrown. His idea is to destroy and occupy it, then keep a merciful rule while charging high tax and establishing an oligarchy.
In Chapter 18, Machiavelli points out that a good ruler should be able ...