Kirsch, Arthur. The Passions of Shakespeare's Tragic Heroes.
Charlottesville: U P of Virginia, 1990.

Thesis: In the "Preface" to his book Kirsch provides a succinct statement of purpose:

The purpose of this book . . . is to renew an appreciation of the timelessness of Shakespeare's genius in dramatizing human actions and feelings. Drawing upon medieval and Renaissance religious ideas as well as both Renaissance and modern conceptions of character, it explores Shakespeare's dramatization of the emotional and spiritual suffering of the heroes in Hamlet, Othello, Macbeth, and King Lear.  (ix)
True to these words, Kirsch illuminates Macbeth's psychology and morality by drawing on St. Augustine's definition of pride, La Primaudaye's reflections on ambition, Montaigne's comments on envy, and Freud's analysis of narcissism. Here is a typical passage:
   For Augustine, self-love, the soul's desire to be its own beginner, to be everything, both results in and is born of emptiness, of nothingness. The Freudian analogue is the self-love of primary narcissism. Echoes of such narcissism exist in all human beings, and in an infant the condition is natural. The regression to such a condition in an adult, however, is truly to confound Hell in Elysium, for . . . the godlike presumption of primary narcissism results in a sense only of the loss of the self, because a self that encompasses everything ultimately cannot be defined by anything, and is indeed defined by nothing. The premise common to both the Augustinian and the Freudian conception is that human beings must exist in relation to a reality outside themselves . . . .
     The Augustinian reverberations of Macbeth's tragedy are explicit and emphatic. Among Macbeth's first words after he has achieved the crown are, "To be thus is nothing" (3.1.49); both he and Lady Macbeth immediately yearn to join the safety and "peace" of the man they have murdered (3.2.8, 22); and the subsequent action progresses inevitably toward the state of mind in which Macbeth sees all of life as
                                    a tale
Told by an idiot, full of sound and fury
Signifying nothing                       (5.5.25-27)
and toward its counterpart in the literal suicide of his wife. . . . A sense of emotional emptiness permeates the play. Lady Macbeth expresses it explicitly soon after the killing of Duncan when she speaks of attaining desire "without content" and of spending all and having "naught"; and it informs Macbeth's actions throughout, in the undercurrent of weariness even in his earlier soliloquies, and in the appalling tedium of feeling and spirit that he exhibits in contemplating his later homicides.  (97-98)

Bottom Line: Offers wisdom of the ages.