Macbeth was influenced; but he consented to be influenced.

From G. K. Chesterton's On a Humiliating Heresy.

But, whatever we may say about Hamlet, we must not say this about Macbeth. Hamlet was only a mild sort of murderer; a more or less accidental and parenthetical murderer; an amateur. But Macbeth was a good, solid, serious, self-respecting murderer; and we must not have any nonsense about him. For the play of Macbeth is, in the supreme and special sense, the Christian Tragedy; to be set against the Pagan Tragedy of Oedipus. It is the whole point about Oedipus that he does not know what he is doing. And it is the whole point about Macbeth that he does know what he is doing. It is not a tragedy of Fate but a tragedy of Freewill. He is tempted of a devil, but he is not driven by a destiny. If the actor pronounces the words properly, the whole audience ought to feel that the story may yet have an entirely new ending, when Macbeth says suddenly, ‘We will proceed no further in this business.’ The incredible confusion of modern thought is always suggesting that any indication that men have been influenced is an indication that they have been forced. All men are always being influenced; for every incident is an influence. The question is, which incident shall we allow to be most influential. Macbeth was influenced; but he consented to be influenced. He was not, like a blind tragic pagan, obeying something he thought he ought to obey. He does not worship the Three Witches like the Three Fates. He is a good enlightened Christian, and sins against the light.