Lady M. What beast was’t, then,
               That made you break this enterprise to me? 
               When you durst do it, then you were a man;
               And, to be more than what you were, you would
               Be so much more the man.  Nor time nor place
               Did then adhere, and yet you would make both: 
               They have made themselves, and that their fitness now
               Does unmake you.  I have given suck, and know
               How tender ’tis to love the babe that milks me: 
               I would, while it was smiling in my face,
               Have pluck’d my nipple from his boneless gums,
               And dash’d the brains out, had I so sworn as you
               Have done to this.

Here Lady Macbeth asserts (1) that Macbeth proposed the murder to her:  (2) that he did so at a time when there was no opportunity to attack Duncan, no ‘adherence’ of ‘time’ and ‘place’:  (3) that he declared he wou’d make an opportunity, and swore to carry out the murder.

Now it is possible that Macbeth’s ‘swearing’ might have occurred in an interview off the stage between scenes v. and vi., or scenes vi. and vii.; and, if in that interview Lady Macbeth had with difficulty worked her husband up to a resolution, her irritation at his relapse, in sc. vii., would be very natural.  But, as for Macbeth’s first proposal of murder, it certainly does not occur in our play, nor could it possibly occur in any interview off the stage; for when Macbeth and his wife first meet, ‘time’ and ‘place’ do adhere; ‘they have made themselves.’  The conclusion would seem to be, either that the proposal of the murder, and probably the oath, occurred in a scene at the very beginning of the play, which scene has been lost or cut out; or else that Macbeth proposed, and swore to execute, the murder at some time prior to the action of the play.[291] The first of these hypotheses is most improbable, and we seem driven to adopt the second, unless we consent to burden Shakespeare with a careless mistake in a very critical passage.

And, apart from unwillingness to do this, we can find a good deal to say in favour of the idea of a plan formed at a past time.  It would explain Macbeth’s start of fear at the prophecy of the kingdom.  It would explain why Lady Macbeth, on receiving his letter, immediately resolves on action; and why, on their meeting, each knows that murder is in the mind of the other.  And it is in harmony with her remarks on his probable shrinking from the act, to which, ex hypothesi, she had already thought it necessary to make him pledge himself by an oath.

Yet I find it very difficult to believe in this interpretation.  It is not merely that the interest of Macbeth’s struggle with himself and with his wife would be seriously diminished if we felt he had been through all this before.  I think this would be so; but there are two more important objections.  In the first place the violent agitation described in the words,