What happens
Falstaff prepares for his third meeting with Mistress Ford at Herne's oak, invoking luck and odd numbers. Mistress Quickly arrives to give him final instructions and promise a chain and horns. After she leaves, Ford enters disguised as Master Brook, and Falstaff boasts of his plans to cuckold Ford and deliver his wife. Falstaff exits eagerly toward the park.
Why it matters
This scene marks the final setup before Falstaff's public downfall. Falstaff's invocation of 'divinity in odd numbers'—a reference to superstition and folk belief—reveals his desperation and the erosion of his rational confidence. He has been beaten, dunked in the Thames, and dressed as a witch, yet he still pursues the same scheme with undiminished appetite. His willingness to try a third time, despite mounting evidence of failure, exposes the core of his character: a man driven by desire and delusion, unable or unwilling to learn. Mistress Quickly's promise of 'horns' is darkly comic—she means the horns he will wear as Herne the hunter, but the audience hears the cuckold's horns he has already earned through his schemes.
Ford's arrival as Master Brook intensifies the trap. Falstaff, speaking to what he believes is his co-conspirator, reveals the full extent of his contempt: he calls Ford 'a poor old man' and brags of reducing him to a 'cuckold.' The irony is exquisite—Ford is literally listening to Falstaff promise to betray him, and Falstaff has no awareness that his listener is the very man he mocks. This scene crystallizes the play's central dynamic: Falstaff operates in a world of self-deception, where his assumptions about other people's thoughts and desires are completely inverted. He believes himself a seducer; he is actually a fool being herded toward a spectacle of public shame.