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".