The local (in 4.3) and the global (the whole play, its world and its action) reciprocally affect each other according to the reader's interpretation or the actor's expression of their relationship and may also be said to effect each other, according to how either is interpreted and given priority, entailing a correlative significance in the other. If the Macbeths have children, or at least a child, then it would be nonsense for Macduff to say Macbeth "has no children." If there is no evidence that the Macbeths at the time of the play's action have children, for all practical purposes they have not. And it matters especially that Macbeth "has no children."

Closest to his wife in our perception when she reads his letter aloud before we see them together and again when they plan and execute their regicidal plot, Macbeth is by degrees cut off first from her, as he becomes progressively more depressed, fearful, and finally desperate; and then from virtually all but Seyton, by which time he has

. . . liv'd long enough: my way of life
Is fall'n into the sere, the yellow leaf,
And that which should accompany old age,
As honor, love, obedience, troops of friends,
I must not look to have; but in their stead,
Curses, not loud but deep, mouth-honor, breath,
Which the poor heart would fain deny, and dare not.

(5.3.22-28)

There is no mention of the unique solace of children, here, and the prospect of living progeny, greater than the earlier greatest, is behind. Macbeth is alone to face his future—his death and his damnation.

Finally, Macbeth's barrenness is significant as an unspecified but implicit motive for his killing others and their children, and it is significant in another—perhaps more—important way as symbolizing a moral desiccation and a spiritual sterility contrasting with the symbolic green thumbs (or fingers) of the "gardener"-kings, both Duncan the unfortunate and too trusting, who in 1.4.28-29 says he has "begun to plant thee [Macbeth], and will labor / To make thee full of growing"; and his son and heir, Malcolm, who, summing up his immediate obligations and responsibilities at the end of the play, says,

What's more to do
Which would be planted newly with the time,

. . . . .

.. . This, and what needful else
That calls upon us, by the grace of Grace,
We will perform in measure, time, and place.

(5.9.30-31, 37-39, emphasis added)