In Act 3, Scene 6, this exchange occurs between Lear and the Fool:
Prithee, nuncle, tell me whether a madman be a gentleman or a yeoman?
A king, a king!
No, he's a yeoman that has a gentleman to his son; for he's a mad yeoman that sees his son a gentleman before him.
The figure of the “madman” here has an echo of which of the Fool’s earlier comments?