The prince of darkness is a gentleman.
– William Shakespeare
King Lear, Act 3, Scene 4. When Gloucester asks Lear has he no better company to keep than Edgar (mad Poor Tom), Edgar makes this reply that Satan himself is a "gentleman". What Edgar is saying here is that the devil comes in all forms, including wearing the disguise of a gentleman. Gloucester has remained naively blind to the true character of his other devilish son Edmund, and has not seen the true goodness of Edgar, disguised here as a beggar and not recognized by Gloucester.