Lady Macbeth’s remarkable strength of will persists through the murder of the king—it is she who steadies her husband’s nerves immediately after the crime has been perpetrated.
The medieval and renaissance view of the world saw a relationship between order on earth, the so-called microcosm, and order on the larger scale of the universe, or macrocosm.
Thus, when Lennox and the Old Man talk of the terrifying alteration in the natural order of the universe (nature), these are all reflections of the breakage of the natural order that Macbeth has brought about in his own microcosmic world (society).
This theme of the relationship between gender and power is key to Lady Macbeth’s character: her husband implies that she is a masculine soul inhabiting a female body, which seems to link masculinity to ambition and violence.
Shakespeare, however, seems to use her, and the witches, to undercut Macbeth’s idea that “undaunted mettle should compose / Nothing but males” (1.7.73–74).