From this one can draw a general conclusion that will never (or hardly ever) be proved wrong: He who is the cause of someone else's becoming powerful is the agent of his own destruction; for he makes his protege powerful either through his own skill or through his own strength, and either of these must provoke his protege's mistrust once he has become powerful.

machiavelli, the prince, ch.3 p.14

The Romans always looked ahead and took action to remedy problems before they developed. They never postponed action in order to avoid a war, for they understood you cannot escape wars, and when you put them off only your opponents benefit.

machiavelli, the prince, ch.3 p.11

There is a general rule to be noted here: People should either be caressed or crushed. If you do them minor damage they will get their revenge; but if you cripple them there is nothing they can do. If you need to injure someone, do it in such a way that you do not have to fear their vengeance.

machiavelli, the prince, ch.3 p.10

compare to thucydides and his modern-day disciple donald kagan, who advise politicians to never take half measures. half measures led to the spartan defeat and the cuban missile crisis, and apparently, if machiavelli is to be believed, to every rebellion against a prince.

Thus, you [as a new prince] make enemies of all those to whom you have given offense in acquiring power, and in addition you cannot keep the goodwill of those who have put you in power, for you cannot satisfy their aspirations as they thought you would.

machiavelli, the prince, ch.3 p.7

...I had begun to think I had, if not lost, then mislaid your goodwill, for you had allowed so long to go by without writing to me, and I was in some uncertainty as to what the reason could be.

machiavelli, introductory letter to francesco vettori in the prince, p.1

All states, all forms of government that have had and continue to have authority over men, have been and are either republics or principalities.

machiavelli, the prince, ch.1 p.6