The Prince by Niccolò Machiavelli (1532)

TL;DR: To stay in Power as a Prince, you must be sly defensively, and offer fear offensively. You must play a certain way, have the right army and allies, and have the right character and behavior.

It is necessary to be a fox to discover the snares, and a lion to terrify the wolves.

This is terrible. Terrible in a stomach churning way. Hence, the term "Machiavellian".

What it is is essentially like a "How to" book for Medieval Princes, Tyrants or modern Dictators alike, to stay in power. There tends to be some reasonable wisdom in the book, but it almost always ends up in inducing force, blood or there having a bias for people being deceptive and evil. Thus, one should act accordingly.

In this quote he basically say: Treat people well or hurt them. And if you must hurt them, hurt them in a way that they can't fight back.

Upon this, one has to remark that men ought either to be well-treated or crushed because they can avenge themselves of lighter injuries, of more serious one they cannot; therefore the injury that is to be done to a man ought to be of such a kind that one does not stand in fear of revenge.

but show some mercy by doing it swiftly

... injuries ought to be done all at one time, so that being tasted less, they offend less, benefits ought to be given little by little, so that the flavor of them may last longer.

And well, if you can't persuade them: force them. (*cringes)

The nature of people is variable, and whist it is easy to persuade them, it is difficult to fix them on that persuasion. And thus it is necessary to take such measures that, when they believe no longer, it may be possible to make them believe by force.

Machiavelli is a confusing fellow. He tells at one time to be forceful, and another to be reminded that all this will not bring you glory.

Yet it cannot be called talent to slay fellow citizens, to deceive friends, to be without faith, without mercy, without religion, such methods may gain an empire, but not glory.

But what it may really be is that, he's saying to princes, you must be both.

A powerful and courageous prince will overcome all such difficulties by giving at one time hope to his subjects that the evil will not be for long, at another time fear of the cruelty of the enemy, then preserving himself adroitly from those subjects who seem to him to be too bold.

And that you must know the dark side; to make use of it when needed. (Sounds exactly like what a Sith Lord would say) Classic "the ends justify the means" argument.

Hence it is necessary for a prince wishing to hold his own to know how to do wrong, and to make use of it or not according to necessity.

If he who rules a principality cannot recognize evils until they are upon him, he is not truly wise and this insight is given to few.

The quote most often attributed to him: 

Upon this question arises: whether it be better to be loved than feared or feared than love?

It may be answered that one should wish to be both, but because it is difficult to unite them in one person, it is much safer to be feared than loved, when of the two either must be dispensed with.

You know the thing I said about having a bias for deception.

He who seeks to deceive will always find someone who will allow himself to be deceived.

Here's one quote where it kinda goes well, until the end where it just blows over. He's saying you're not supposed to take in unsolicited advice, but you must be a perpetual learner. And when someone tells you fake news, be very mad at them.

a prince, therefore, ought always to take counsel, but only when he wishes and not when others wish; he ought rather to discourage every one from offering advice unless he asks it; but however, he ought to be a constant inquirer, and afterwards a patient listener concerning the things of which he inquired, also on learning that any one on any consideration, has not told him the truth, he should let his anger be felt.

One seemingly good wisdom in all this is to not be reliant on fortune. Fortune, assuming he means in this way as something that can't be controlled, something exerted upon externally. Then Machiavelli explains it in a polarizing way.

He who has relied  least on fortune is established the strongest.

It is a common defect in man not to make any provision in the calm against the tempest.

The prince who relies entirely upon fortune is lost when it changes 

Regarding Fortune still, but with a terrible terrible analogy, generously sprinkled with misogyny.

for my part I consider that it is better to be adventurous than cautious, because fortune is a woman, and if you wish to keep her under it is necessary to beat and ill-use her; and it is seen that she allows herself to be mastered by the adventurous rather than by those who go to work more coldly. She is therefore always woman like, a lover of young men, because they are less cautious, more violent, and with more audacity command her.

Finally, God has done everything for you. What you do next is on your own Free Will.

further than this, how extraordinarily the ways of God have been manifested beyond example: the sea is divided, a cloud has poured forth water, it has rained manna, everything has contributed to your greatness; you ought to do the rest. God is not willing to do everything, and thus take away our free will and that share of glory which belongs to us. 

Hard to say what Machiavelli's motivations were in this. Some parts of this book read something like out of the movie, The Godfather, very disturbing. I've heard of arguments viewing it as being satirical. But that doesn't quite fit. If anything, it seems like a trade off between being good and political effectiveness. The current thinkers nowadays preach that short term, ruthlessness works; for the long game, being nice triumphs.