No sooner have the witches vanished than Banquo begins to doubt whether there had been “such things there as they did speak about.”  This is the natural incredulity of a free mind so circumstanced.  On the other hand, Macbeth, whose manner, since the first announcement of the sisters, has been that of a man in a reverie, makes no doubt whatever of the reality of their appearance, nor does he reply to the expressed scepticism of Banquo, but abruptly exclaims, “your children shall be kings.”  To this Banquo answers, “you shall be king.”  “And thane of Cawdor too:  went it not so?” continues Macbeth.  Now, what, in either case, is the condition of mind which can have given rise to this part of the dialogue?  It is, we imagine, sufficiently evident that the playful words of Banquo were suggested to Shakspere by the narration of Holinshed; but how are we to account for those of Macbeth, otherwise than by supposing that the question of the crown is now settled in his mind by the coincidence of the principal prediction, with the shapings of his own thoughts, and that he is at this moment occupied with the wholly unanticipated revelations, touching the thaneship of Cawdor, and the future possession of the throne by the offspring of Banquo?

Now comes the fulfilment of the first prophecy.  Mark the words of these men, upon receiving the announcement of Rosse: 

  “Banquo.  What! can the devil speak truth?
  Macbeth.  The thane of Cawdor lives:  why do you dress me
  In borrowed robes?”

Mark how that reception is in either case precisely the reverse of that given to the prophecy itself.  Here Banquo starts.  But what is here done for Banquo, by the coincidence of the prophecy with the truth, has been already done for Macbeth, by the coincidence of his thought with the prophecy.  Accordingly, Macbeth is calm enough to play the hypocrite, when he must otherwise have experienced surprise far greater than that of Banquo, because he is much more nearly concerned in the source of it.  So far indeed from being overcome with astonishment, Macbeth still continues to dwell upon the prophecy, by which his peace of mind is afterwards constantly disturbed,

  “Do you not hope your children shall be kings,
  When those that gave the thane of Cawdor to me
  Promised no less to them?”

Banquo’s reply to this question has been one of the chief sources of the interpretation, the error of which we are now endeavouring to expose.  He says,

    “That, trusted home,
  Might yet enkindle you unto the crown,
  Besides the thane of Cawdor.  But, ’tis strange;
  And often times, to win us to our harm,
  The instruments of darkness tell us truths,
  Win us with honest trifles, to betray us
  In deepest consequence.”

Now, these words have usually been considered to afford the clue to the entire nature and extent of the supernatural influence brought into play upon the present tragedy; whereas, in truth, all that they express is a natural suspicion, called up in the mind of Banquo, by Macbeth’s remarkable deportment, that such is the character of the influence which is at this moment being exerted upon the soul of the man to whom he therefore thinks proper to hint the warning they contain.