Question

Why did the guest at the at the feast think that macbeth had gone mad?

Answer 1

Banquo suspects Macbeth but gains comfort from the second part of the Witches' prediction — that his own children will be kings. Having announced his intention to go riding with Fleance, Banquo is persuaded by the Macbeths to return later that evening to their new palace at Forres for a special feast. However, Macbeth realizes that the Witches' prophecy regarding Banquo represents a threat to his own position. Unable to endure the thought of Banquo's descendants claiming his position, Macbeth summons two hired murderers and confirms with them prior arrangements for the killing of Banquo and Fleance.