Lady Macbeth, like all in Shakespeare, is a class individualised:--of high rank, left much alone, and feeding herself with day-dreams of ambition, she mistakes the courage of fantasy for the power of bearing the consequences of the realities of guilt. His is the mock fortitude of a mind deluded by ambition; she shames her husband with a superhuman audacity of fancy which she cannot support, but sinks in the season of remorse, and dies in suicidal agony. Her speech:--
... "Come, you spirits That tend on mortal thoughts, unsex me here," &c.--
is that of one who had habitually familiarised her imagination to dreadful conceptions, and was trying to do so still more. Her invocations and requisitions are all the false efforts of a mind accustomed only hitherto to the shadows of the imagination, vivid enough to throw the every-day substances of life into shadow, but never as yet brought into direct contact with their own correspondent realities. She evinces no womanly life, no wifely joy, at the return of her husband, no pleased terror at the thought of his past dangers, whilst Macbeth bursts forth naturally--
and shrinks from the boldness with which she presents his own thoughts to him. With consummate art she at first uses as incentives the very circumstances, Duncan's coming to their house, &c., which Macbeth's conscience would most probably have adduced to her as motives of abhorrence or repulsion. Yet Macbeth is not prepared:--
_Ib._ sc. 6. The lyrical movement with which this scene opens, and the free and unengaged mind of Banquo, loving nature, and rewarded in the love itself, form a highly dramatic contrast with the laboured rhythm and hypocritical over-much of Lady Macbeth's welcome, in which you cannot detect a ray of personal feeling, but all is thrown upon the "dignities," the general duty.
"We will proceed no further in this business: He hath honour'd me of late; and I have bought Golden opinions from all sorts of people, Which would be worn now in their newest gloss, Not cast aside so soon."
Note the inward pangs and warnings of conscience interpreted into prudential reasonings.
"A heavy summons lies like lead upon me, And yet I would not sleep. Merciful powers! Restrain in me the cursed thoughts, that nature Gives way to in repose."