Is Macbeth high when he sees the witches?
After Macbeth and Banquo see the witches for the first time (Act 1, Scene 3), there is this exchange:
The earth hath bubbles as the water has,
And these are of them. Whither are they vanish'd?
Into the air, and what seem'd corporal melted
As breath into the wind. Would they had stay'd!
Were such things here as we do speak about?
Or have we eaten on the insane root
That takes the reason prisoner?
Certainly they are both filled with disbelief and wonder, and maybe they're even laughing about having seen and talked to the witches. There is no suggestion, though, that they have eaten anything, like an "insane root," that made them hallucinate or high.
But much later in the play, when Macbeth sees the witches for the last time (Act 4, Scene 1), they have made quite a disgusting concoction in their bubbling cauldron. They have made "the gruel thick and slab" and perhaps they have cooled it "with a baboon's blood" so that Macbeth can better drink it. I have seen a number of versions of the play wherein Macbeth does, indeed, drink from a cup or ladle dipped in the cauldron's gross gruel. Now, whether this makes him high, or just more susceptible to the prophecies of the apparitions, is an open question. What do you think?