‘Tis the infirmity of his age: yet he hath ever
but slenderly known himself.

– William Shakespeare

King Lear, Act 1, Scene 1. Regan attributes her father Lear’s changed personality and poor judgment in banishing Cordelia to the senility of old age. She also hits the nail on the head when she pinpoints Lear’s fatal flaw: he has no self-knowledge. While he developers self-knowledge later in the play, it comes too late to save him from his tragic fate.