This scene and the next should be considered together, for both deal with the question of treachery and loyalty, and both consider the nature of genuine courage, as opposed to the arrogant bravado of Macbeth.
Here is a woman apparently abandoned by her husband. She has been left to fend for her children like a mother bird in the nest. Even the tiny wren would show more spirited defense of her own family against a predator than Macduff has done, she argues. Her conclusion can be only that her husband "wants the natural touch" — that is, he lacks human kindness. It's interesting to hear in this phrase an ironic echo of the words of Lady Macbeth, who accused her husband of having precisely too much of "the milk of human kindness."
Ross' speech diverts Lady Macduff's justifiable anger away from her husband, whom he calls "noble, wise, judicious," toward the cruelty of the circumstances in which the country as a whole finds itself. The terror of Macbeth's Scotland is that no one can be sure of another's loyalty or treachery "when we are traitors, / And do not know ourselves; when we hold rumour / From what we fear, yet know not what we fear" (18–20).
