Fergusson, Francis. "Macbeth as the Imitation of an Action."
English Institute essays: 1951. Ed. Alan S. Downer. New York: AMS Press, 1952. 31-43.

Thesis: Fergusson's main concern is to demonstrate the unity of Macbeth. Here is Fergusson's own summation of his essay:

To sum up: my thesis is that Macbeth is the imitation of an action (or motive) which may be indicated by the phrase "to outrun the pauser, reason." I have tried to suggest how this action is presented in the metaphors, characters, and plot of the first two acts; and also in the peripeteia, with pathos and recognitions, the great scene between Malcolm, Macduff, and Ross.  (43)

Fergusson begins his essay with a definition of "action" as "not outward deeds or events," but as an "action, or motive, which governs the psyche's life" (32). In Macbeth "all of the characters, in the irrational darkness of Scotland's evil hour, are compelled in their action to strive beyond what they can see by reason alone" (34) and "Shakespeare associates [reason] with nature and nature's order" (34), so that "to outrun reason is . . . to violate nature itself, to lose the bearings of common sense and custom, and to move into a spiritual realm bounded by the irrational darkness of hell one way, and the superrational grace of faith the other way" (35). Macbeth goes into the darkness of hell, irrationally putting his faith in the unnatural Witches, and Malcolm displays faith that God will support his cause.

Evaluation: There's more to it than I've summarized, but not enough more. Fergusson is persuasive, but the essay would be more persuasive if it had more detail.

Bottom Line: Solid, but dull.