This above all: to thine own self be true,
And it must follow, as the night the day,
Thou canst not then be false to any man.

– William Shakespeare

Hamlet, Act 1, Scene 3. Polonius’ final piece of very wise advice to Laertes, as he is about to take the boat to Paris. He counsels his son to remain true to himself and follow his own conscience rather than be guided by the example or influence of others. If he does that then he will be truthful to other people, Polonius believes. But Polonius is a man who doesn’t practice what he preaches. While he gives his son this advice he continues to scheme, sends someone to Paris to spy on Laertes as he indulges his student life, and also spies on his daughter Ophelia and interferes with her romantic life, ultimately contributing to her suicide. He is a liar and a treacherous and deceiving man. Which makes his moral advice so full of irony.