This pope broke every promise he ever made and never once got caught

Niccolò Machiavelli tells a short, pointed story about Pope Alexander the sixth that he clearly expects his reader to find shocking and instructive at once. Alexander, he writes, had no care or thought in the world except how to deceive people, and he always found material to work with. Nobody, Machiavelli says, made promises with more solemn protestations, and nobody kept fewer of them. And yet, because Alexander understood exactly how gullible people are about appearances, his frauds always succeeded.

That story sits at the center of one of Machiavelli's most notorious arguments: that a ruler who wants to survive cannot always keep his word, and shouldn't try to. His reasoning is built around an image borrowed from old writers who described Achilles being raised half by a man and half by Chiron the centaur, who was part beast. The lesson Machiavelli draws is that a ruler needs two natures at once. He must fight like a lion, using open strength, but he also needs the cunning of a fox, because a lion alone can't see a trap, and a fox alone can't fight off wolves. Relying only on the lion, on strength and plain dealing, is a mistake, because if everyone kept their word honestly, keeping yours would be fine policy. But people don't, Machiavelli says flatly, so you're not bound to be more honest with them than they would be with you.

None of this, he's careful to add, means broadcasting your dishonesty. Quite the opposite. A ruler should be extremely good at seeming faithful, merciful, and upright, because, as Machiavelli puts it, everyone sees what you appear to be, but very few ever get close enough to know what you actually are, and even those few won't dare contradict the majority once the majority has decided who you are. This is why Alexander's reputation for piety and his actual conduct could be worlds apart without ever catching up with him during his lifetime: he never let the mask slip in public, only in the private calculation of who to betray next and when.

Machiavelli's own summary is almost a warning label: it is not essential that a ruler possess every good quality, but it is essential that he seem to possess them, because a ruler who lives by them literally, without exception, in a world where others don't, will be undone by people who don't play by the same rules.

Start by treating every commitment as good only for as long as the conditions that produced it still hold, rather than as a debt owed regardless of circumstance. Put real effort into the visible parts of your reputation, because almost everyone around you is judging from a distance, going on what they can see rather than what they can verify. Keep your private read on shifting circumstances separate from what you show the world, and adjust your actual plans quietly rather than announcing every recalculation. Above all, guard against ever letting your public face slip, because one visible act of bad faith will cost you more credibility than years of careful appearance took to build.