At this point Lady Macbeth exclaims, ‘Help me hence, ho!’ Her husband takes no notice, but Macduff calls out ‘Look to the lady.’  This, after a few words ‘aside’ between Malcolm and Donalbain, is repeated by Banquo, and, very shortly after, all except Duncan’s sons exeunt. (The stage-direction ‘Lady Macbeth is carried out,’ after Banquo’s exclamation ‘Look to the lady,’ is not in the Ff. and was introduced by Rowe.  If the Ff. are right, she can hardly have fainted away.  But the point has no importance here.)

Does Lady Macbeth really turn faint, or does she pretend?  The latter seems to have been the general view, and Whately pointed out that Macbeth’s indifference betrays his consciousness that the faint was not real.  But to this it may be answered that, if he believed it to be real, he would equally show indifference, in order to display his horror at the murder.  And Miss Helen Faucit and others have held that there was no pretence.

In favour of the pretence it may be said (1) that Lady Macbeth, who herself took back the daggers, saw the old King in his blood, and smeared the grooms, was not the woman to faint at a mere description; (2) that she saw her husband over-acting his part, and saw the faces of the lords, and wished to end the scene,—­which she succeeded in doing.

But to the last argument it may be replied that she would not willingly have run the risk of leaving her husband to act his part alone.  And for other reasons (indicated above, p. 373 f.) I decidedly believe that she is meant really to faint.  She was no Goneril.  She knew that she could not kill the King herself; and she never expected to have to carry back the daggers, see the bloody corpse, and smear the faces and hands of the grooms.  But Macbeth’s agony greatly alarmed her, and she was driven to the scene of horror to complete his task; and what an impression it made on her we know from that sentence uttered in her sleep, ’Yet who would have thought the old man to have had so much blood in him?’ She had now, further, gone through the ordeal of the discovery.  Is it not quite natural that the reaction should come, and that it should come just when Macbeth’s description recalls the scene which had cost her the greatest effort?  Is it not likely, besides, that the expression on the faces of the lords would force her to realise, what before the murder she had refused to consider, the horror and the suspicion it must excite?  It is noticeable, also, that she is far from carrying out her intention of bearing a part in making their ‘griefs and clamours roar upon his death’ (I. vii. 78).  She has left it all to her husband, and, after uttering but two sentences, the second of which is answered very curtly by Banquo, for some time (an interval of 33 lines) she has said nothing.  I believe Shakespeare means this interval to be occupied in desperate efforts on her part to prevent herself from giving way, as she sees for the first time something of the truth to which she was formerly so blind, and which will destroy her in the end.