The unguarded Duncan?

But the will which was strong enough to hold down conscience gave way for a moment before an instinct of feminine tenderness:

ii. ii. 13.

Had he not resembled

My father as he slept, I had done 't.

The superiority, however, of the intellectual mind is seen in this, that it can nerve itself from its own agitation, it can draw strength out of the weakness surrounding it, or out of the necessities of the situation: must is the most powerful of spells to a trained will. And so it is that Lady Macbeth rises to the occasion when her husband fails. At first Macbeth in the perpetration of the murder appears in his proper sphere of action, and we have already noticed how the Dagger Soliloquy shows no shrinking, but rather excitement on the side of exultation. The change in him comes with a moment of suspense, caused by the momentary waking of the grooms: ii. ii. 24.'I stood and heard them.' With this, no longer sustained by action, he utterly breaks down under the unfamiliar terrors of a fight with his conscience. His prayer sticks in his throat; his thoughts seem so vivid that his wife can hardly tell whether he did not take them for a real voice outside him.

Who was it that thus cried? Why, worthy thane,

You do unbend your noble strength, to think

So brainsickly of things.

In his agitation he forgets the plan of action, brings away the daggers instead of leaving them with the grooms, and finally dares not return to finish what he has left uncompleted. And accordingly his wife has to make another demand upon her overwrought nature: with one hysterical jest,