The phrase "To thine own self be true" was said by Polonius, a counsellor to King Claudius, in Act 1, Scene 3 of William Shakespeare's play, Hamlet. Polonius speaks this line as part of a longer piece of advice to his son Laertes, urging him to be honest and true to himself. The meaning is essentially to be true to one's own nature and principles, which will naturally lead to honesty with others. Polonius' advice is often noted for its irony, as he himself is a somewhat hypocritical character in the play.