Macbeth dismisses reports of invasion by trusting to the prophecies of the apparitions, which seemed to promise him invincibility in battle. When a servant enters to announce the approach of a huge army, Macbeth appears momentarily to lose courage and then angrily spurns his servant and orders his armor to be put on. The Doctor, whose news concerning Lady Macbeth is just as grim, is treated with similar contempt.
Macbeth's tone is typically brazen. The reports he has heard can have no consequence, given the prophecies of the three apparitions of Act IV, Scene 1. Throughout this scene, any doubts he may have are quelled by his bold imperatives: "Bring me no more reports," "Fly, false thanes," and more. We see a man completely self-assured, a "confident tyrant," as Siward calls him in the subsequent scene. These angry words do much to assert his own manhood, in contrast to the cowardice he perceives in others — not only his servant, whom he calls "cream-faced" and "lily-livered," but also the rebel soldiers, whom he insultingly refers to as "epicures" (that is, self-indulgent and lazy).
In the dialogue with the servant, Macbeth orders him to "prick his cheeks" in order to "put colour" back in his face, an ironic reminder of the earlier color symbolism when Macbeth was accused by his wife of having a white heart, as opposed to her own red hands. Another imperative — "Give me my armour" — has to be repeated when Macbeth's armourer, Seyton, initially refuses to do so. Similarly, when the Doctor confesses that he has been unable to cure Lady Macbeth's madness, Macbeth mocks his ability, challenging him to "Throw physic (medicine) to the dogs."
But there is also another Macbeth, who admits to being "sick at heart" and who feels he has entered the season of the "yellow leaf," that is, literally, the fall of his own reputation; and who, in a further moment of self-realization, recognizes the sickness of his own land: "If thou could'st, Doctor, cast / The water of my land, find her disease, / And purge it to a sound and pristine health / I would applaud thee to the very echo / That should applaud again" (50-54).
Earlier, referring to his wife's sickness, Macbeth has questioned the doctor's ability to remove from her those thoughts and feelings "Which weigh upon the heart." The Doctor's response: "Therein the patient must minister to himself" is particularly interesting. Where we expect "herself," Shakespeare instead uses the masculine pronoun, referring to a patient of either sex, particularly in proverbial statements such as this one. The suggestion is that Macbeth, too, must find the cure to his own disease. Macbeth's military preparation, which the Doctor says he has heard about, is unlikely to be any more effective than a medicinal preparation or remedy which he might prescribe for the sick nation of Scotland.
English epicures (8) the self-indulgent English
sway (9) command
goose (12) cowardly
sere (23) dry
fain (28) rather
skirr (35) scour
oblivious (43) that brings oblivion
physic (47) medicine
cast the water (50) examine the urine (here, used metaphorically)
rhubarb . . . drug (55) purgatives