Tools of Characterization
Those who can, do. And in Macbeth, those who can't just … think about talk about it a lot, which may actually be the better course of action.
Macbeth's growth towards being a full-blown tyrant can be mapped by how often he talks and thinks about what he's about to do. It takes many scenes of thought and talk for Macbeth to kill Duncan, but later, he decides to off Macduff's whole family in one fell swoop because Macduff's name is mentioned. For Macbeth, thought often inhibits action, and if action is a sign of manliness and power, it's something he can always use a little more of.
Lady Macduff is a loving and doting mother who banters with her son; Lady Macbeth calls on spirits to "unsex" her (1.5.48) and claims that she knows "How tender 'tis to love the babe that milks me" (1.7.63) but says that she wouldn't hesitate to tear a child from her breast and bash its brains if she had promised her husband she would do it (1.7.66-67).
Yeah, we'll say that family life is an important method of characterization.
Appearances can be deceptive—unless they aren't. We know the weird sisters are, well, weird because they're bearded (1.3.48), and we know that a man is honorable if he's bleeding from the front. King Duncan insists that the bloody Captain's gashes "speak" volumes about his heroic deeds (1.2.52) and Young Siward is deemed a "man" when his corpse is discovered to have wounds on the front of his body, a sign that he was not killed while running away (5.8.48).
If only it were always so easy.