On Predestination

and plays:

...Predestined, as it were, in the wake of the witches' predictions to commit precisely such butcheries as must occur in order to fulfill the dark prophecies set out in the opening scene, what else is the poor man to do? Is he not as much victim as villain? Constrained by the sheer predictive force of supernatural witchery—driven mad, in other words, by such "vaulting ambition" (1.7.27) as to encompass the very throne of Scotland itself—where else but the killing fields do we expect to find Macbeth? Is he not ineluctably drawn to such extremities by the pressure of events? Events that he can neither control nor escape but that will, in the end, consume him as well? Certainly, then, he will choose the path of violence, the fixed machinery of the play having precluded all other possibilities.

So declares the sceptic when faced with the seeming iron necessity of the play's action.

Here, then, is the question on which the play turns; indeed, the answer will determine whether or not we actually have a play. For if it cannot be shown that Macbeth is free to act otherwise, free to refuse the promptings of the vile spirits, whose blueprint for him is one of mounting villainy followed by despair and destruction, then there can be no play. A world in which the choices we make do not finally matter, because our wills are already fixed beneath the weight of a crushing determinism, is not a human world...