In act 3 scene 4 of Macbeth, Macbeth says "what man I dare, I dare... / Unreal mockery, hence." What is the irony of Macbeth's words to the...

After killing Duncan in order to ensure the prophecies of
the witches, Macbeth finds himself blinded by his ambition and power. So he hires
murderers to kill Banquo lest his sons prevent Macbeth from attaining his ambition. In
the meantime, as he and Lady Macbeth discuss their plans, they agree to dissemble before
their guests are soon to arrive; Lady Macbeth tells her
husband,

Come on, Gentle my lord, sleek
o'er your rugged looks;

Be
bright and jovial among your guests tonight.
3.2.30-31)

Macbeth
replies,

So shall I, love, and so, I pray be
you:

Let your
remembrance apply to banquo;

Present him eminence, both
with eye and tongue:

Unsafe the while, that we must
lave

Our honors in these flattering
streams

And make our faces vizards to out
hearts

Disguising what they are. 
(3.2.32-38)

Ironically,
however, it is Macbeth who has cautioned his wife, that becomes overpowered by guilt and
fear at the banquet, having learned from the murderers that Fleance has escaped. In this
anxiety, he sees Banquo's ghost at the banquet and disconcerted, loses his earlier
confidence. While he accuses the ghost of Banquo of an "unreal mockery," it is his own
paranoia and guilt that mocks Macbeth himself, thus creating yet another
irony.