After 500 years, it is still hard to know what to make of Niccolo Machiavelli's The Prince. We've think we know what it all means - but do we? Unlike most of history's iconic figures, Machiavelli hasn't been rewritten with each passing generation: He's always been a first-rate bastard. If nothing else, that's integrity.

But is it fair? Machiavelli maintains that the only way to hold power is to do right by your people. The Prince may be devoid of angles singing but it is a brilliant and plain-spoken explanation of the mechanics of the real world - whether you're running for office or trying to get ahead at work. Best not to use on relationships... we really can't stress that enough.