Here is a previous anwser on another reddit, but in summation The Prince transformed how Philosophers look at politics, The Prince in the words of D. H. Dunning is " Completely dissevered from older accepted systems of political theory as the discovery of America by his contemporary Christopher Columbus is dissevered from the older accepted systems of geography" Many scholars consider Machiavelli to be the father of Political Science, almost all works written about the state before his time were written about the how a state ought to be governed, how states should prosper by being ethical institutions within themselves that were in tune with the divine/natural order( e.g. Plato's Republic). Rather than talk about how states ought to be governed Machiavelli discussed how in actuality politics and power was rendered as he witnessed the political turmoil around at the end of the Italian Renaissance. Rather than being an "instrument for the achieving of the good life, [the State is] a dynamic, amoral entity, a force". Machiavelli thus humanized politics, his quote that "Hence it is that all armed prophets have conquered, and the unarmed ones have been destroyed" best captures the idea that politics is ultimately a human affair, one that involves instilling both loyalty and fear, playing off of the irrationality of the masses, and at time being willing to act boldly outside of divine law in order to keep order. This is a very simple response I have given, there have been volumes written on the subject of Machiavelli's thought, He was a much more deeper thinker whose other works ( about Republics) almost seem to go against the cartoonish notions of Machiavellianism. The Price was a book he wrote in one of the darkest episodes of his life when he was exiled and trying to win the favor of a new patron by written this primer on how one gains and keeps power. Even though it is less than 100 pages it was his most influential work that transformed western political theory. Christian Gauss, Introduction to the Prince Harvey C. Mansfield Jr. Machiavelli's Political Science