How did the prophecy of the witches affect Macbeth in Shakespeare's Macbeth?

From the outset, the witches' predictions
have a marked effect on Macbeth, so much so that Banquo notices Macbeth's
response during their encounter with them. Banquo remarks, in Act 1, scene
3:

Good sir,
why do you start; and seem to fear
Things that do sound so
fair?

It is clear at this
point that Macbeth finds credence in the witches'
predictions that he will become Thane of Cawdor and that he shall be
king. Banquo's comment seems to indicate that Macbeth has a fright on hearing these
words, probably because the witches have so accurately reflected his own 'deep and dark
desires' - his ambition to be king. In the same scene Banquo also tells Angus and
Ross:

Look,
how our partner's rapt.

It is
clear that Macbeth has been enraptured by what the witches have
said. Banquo later also reflects on the effect that the predictions have
had on Macbeth when he muses in Act 3, scene 1:

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Thou hast it now: king, Cawdor, Glamis,
all,
As the weird women promised, and, I
fear,
Thou play'dst most foully
for't:

It is
clear that Banquo suspects Macbeth of murdering King Duncan. He suggests that Macbeth
had used foul means to achieve what the witches had
predicted.

Macbeth is clearly overwhelmed by
what the witches predict. On being informed by Ross that he had been
given the title thane of Cawdor, he responds as follows in an
aside:

Glamis,
and thane of Cawdor!
The greatest is
behind.

He clearly believes
that the greatest hurdle to his 'overriding ambition' has been overcome and that it
would be easy to achieve his goal. This is further emphasized when, again in an aside,
he comments:

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Two truths are told,
As happy prologues
to the swelling act
Of the imperial
theme.

Macbeth is clearly
ecstatic that he now holds two titles and he believes that they are precursors to his
holding the highest title of all, that of king of
Scotland.

So overjoyed is Macbeth by the predictions and
the positive result, he believes stems from them - becoming thane of Cawdor, that he
immediately forwards a missive to his wife informing her of the grand news. He asks her
'to lay it' to her heart. Macbeth is certain about achieving the
crown.

When he arrives at his castle later, he and Lady
Macbeth immediately start plotting Duncan's murder. Macbeth is plainly
spurred on by the predictions and although he expresses some doubt about
the plot later, he is easily persuaded by his wife to
continue.

Macbeth has so much faith in the
accuracy of the witches' predictions, that he, at the pinnacle of his tyranny, seeks
them out to provide him with more assurances. The witches tell him
that,

none of
woman born shall harm
Macbeth

and
that:

Macbeth
shall never vanquish'd be until
Great Birnam wood to high Dunsinane
hill
Shall come against
him.

Macbeth
takes the witches at their word and believes that he is practically
invincible since the two predictions state propositions which are
naturally impossible. So confident is he that he
states:

That
will never be
Who can impress the forest, bid the tree
Unfix his
earth-bound root? Sweet bodements! good!
Rebellion's head, rise never till the
wood
Of Birnam rise, and our high-placed
Macbeth
Shall live the lease of nature, pay his
breath
To time and mortal
custom.

Macbeth
does not realise that he has been deceived by equivocation and double-speak and he
relentlessly continues on his destructive path towards his own
doom.