Why does Macbeth seek the witches after Act 3, Scene 4's banquet?

During the banquet in Act III, Scene IV, Macbeth learns that Banquo has been killed (as he ordered) but that Fleance, Banquo's son, has escaped. Remember that back in Act I, Scene III, the witches made three prophecies and that the last of these stated that Banquo's sons would rise to become kings. Macbeth is, therefore, very worried that Banquo's son, Fleance, will overthrow him and become the king of Scotland. At the banquet, Macbeth expresses this fear through the following lines:

"Then comes my fit again. I had else been perfect."

For Macbeth, then, seeing the witches again is important because it will help him to determine whether Fleance is indeed a threat to his throne. After all, everything that the witches told Macbeth has so far come true: he became the Thane of Cawdor and then the King of Scotland. Now he needs to know if Fleance will really take his kingdom and if any other threats may cross his path.

In Macbeth, why does Macbeth meet the witches outside the castle in Act 4?

In Act 4 of Macbeth, Macbeth does not summon the witches inside the castle because he does not have the authority to do so. Macbeth is the king of Scotland, which by rights gives him authority over men who are his subjects. He can order around the people of Scotland as he pleases. The witches, however, are elements of the natural order and harbingers of fate and destiny--they are not Macbeth's subjects. Therefore, Macbeth has no authority to summon the witches to come to his castle. He does want to get another prophecy as he understands and trusts that the witches are reporting the truth regarding future events, so he seeks them out in their lair to get a report. And even when he gets there and demands that the witches give him another prophecy, they remind him that they do not have to yield to his demands.

In Macbeth, what could be the witches' motivation for tricking Macbeth?

The witches, who are also called "the three sisters," an allusion to the mythological goddesses who controlled the fate of humans, delight in manipulating mortals.

This manipulation of the lives of mortals enhances their sense of power as well as providing them enjoyment. In Act I, Scene 3, for instance, the three witches boast to one another of their accomplishments, their evil and disrupting acts. For instance, because a sailor's wife would not share her chestnuts with the first witch, the evil spirit decides to whip up a terrible storm for the husband who is at sea":

But in a sieve I'll thither sail,
And, like a rat without a tail,
I'll do, I'll do, and I'll do. (3.1.7-10)

Certainly, these evil sisters are an intrinsic part of Shakespeare's play, fueling the character faults of Macbeth and motivating his ambitious actions; for instance, when they call him the Thane of Cawdor and Macbeth is later awarded this title by King Duncan, Macbeth then believes that the witches know the future.  This credulity allows the witches much pleasure as they can exercise their many dark machinations.

In addition to their important contributions to the plot of Macbeth, the witches reinforce the cultural beliefs of the Elizabethans who felt that the supernatural played an intrinsic part in their lives. 

What is the motive of the witches in Macbeth?

The Weird Sisters are pure evil. They have dark, Satanic powers which they use to gain control over the forces of nature and manipulate people for their own ends. One such individual is Macbeth, a previously brave, noble warrior turned blood-thirsty tyrant by his dabbling in the forces of darkness.

As women—albeit women with beards—the witches have little or no power in this traditional, male-dominated society. Summoning up the forces of darkness is one of the few ways open to them to impose themselves on others. Their evil powers put them at the center of things, allowing them to play an important part in political affairs of great national importance. It says something about this society that women—whether it's the Weird Sisters or Lady Macbeth—can only exercise meaningful influence by resorting to the most wicked of acts.

What is the motive of the witches in Macbeth?

The three witches like to cause trouble. This is demonstrated at the beginning of Act I, Scene 3. The Second Witch tells the First Witch that she has been killing swine. Evidently, this is just one of the things the Second Witch enjoys doing. The First Witch tells the other two that she intends to get revenge on a sailor's wife who refused to give her chestnuts.

Her husband's to Aleppo gone, master o’ the Tiger;

But in a sieve I'll thither sail,

And, like a rat without a tail,

I'll do, I'll do, and I'll do.

The other two witches are eager to help their sister. Both promise to give her winds to enable her to sail towards Aleppo in her sieve. They listen with obvious pleasure as the First Witch tells them how she plans to torment the husband of the girl who refused to share her chestnuts.

I myself have all the other,

And the very ports they blow,

All the quarters that they know

I’ the shipman's card.

I will drain him dry as hay:

Sleep shall neither night nor day

Hang upon his penthouse lid;

He shall live a man forbid.

Weary se'n nights nine times nine

Shall he dwindle, peak, and pine;

Though his bark cannot be lost,

Yet it shall be tempest-tost.

This is quite a cruel revenge to be taking over a few chestnuts. If the three witches spend their time causing trouble and take such delight in doing so, then it seems possible that their sole intention in meeting Macbeth and Banquo in this scene is to cause the two men trouble, and, further, that none of the troubles would have occurred if they had not made their predictions. In that case, it may be that these wicked creatures are devious enough to invent lies calculated to cause the maximum trouble for both men.

They tell Macbeth that he will be king of Scotland, and they tell Banquo that he will be the sire of future Scottish kings, although he will not be a king himself. Both prophecies may be utter lies. Macbeth has been thinking of murdering Duncan in order to usurp him. The witches' prophecy only encourages him to give the idea deeper consideration. He writes a letter to his wife in which he tells her about his meeting with the witches. Lady Macbeth reads the letter aloud at the beginning of Act I, Scene 5.

They met me in the day of success, and I have learned by the perfectest report, they have more in them than mortal knowledge. When I burned in desire to question them further, they made themselves air, into which they vanished. Whiles I stood rapt in the wonder of it, came missives from the King, who all-hailed me "Thane of Cawdor"; by which title, before, these weird sisters saluted me, and referred me to the coming on of time with "Hail, King that shalt be!" This have I thought good to deliver thee, my dearest partner of greatness, that thou mightst not lose the dues of rejoicing, by being ignorant of what greatness is promised thee. Lay it to thy heart, and farewell.

This letter spreads the witches' possibly false information further. Lady Macbeth is, as she says, "transported." She will become the most important instrument in carrying out the witches' destructive plans. Macbeth kills Duncan and his two guards. Duncan's two sons flee for their lives, enabling Macbeth to blame Duncan's murder on them and become king of Scotland, as predicted.

Then, the hypothetically false predictions of the three witches work further troubles. In fact, it might be said that all the troubles in the play emanate from the witches' evil minds. Macbeth and Banquo now hate and fear each other. Macbeth arranges to have Banquo and his son Fleance ambushed. Banquo is killed, but Fleance escapes, so there is still the possibility that the prophecy will come true that Banquo's descendants will be kings of Scotland.

Macbeth becomes a tyrannical ruler. Evidently, he finds it necessary to rule by terror because everyone hates him. They know he murdered Duncan and had Banquo murdered. The whole country falls into chaos. Is this another result of the witches' wicked planning? The English king sends an army to Scotland, and Macduff kills Macbeth in a death duel. The troubles created by the Weird Sisters finally come to an end. Macbeth realizes he has been tricked.

And be these juggling fiends no more believed,

That palter with us in a double sense,

That keep the word of promise to our ear,

And break it to our hope.

It might be maintained that the three witches had no other motive from the very beginning than to cause troubles—and they certainly succeeded. The audience is left guessing as to whether the witches acted independently to lie and manipulate Macbeth or if they truly were reporting inevitable prophecies.

In Macbeth, what is the witches' motivation for their actions towards Macbeth?

In the Elizabethan age there was a renewed interest in the supernatural and people blamed unexplainable events such as the Plague upon the work of witches, especially what was termed "black witches."  Such "black witches" were the three in "Macbeth."  Their purpose is to create evil and manipulate human beings in order to create havoc and harm.

In "Macbeth" Shakespeare employs the witches for several reasons.  Opening the play with the thunder, darkness, and three witches stirring a cauldron creates great dramatic effect, attracting the attention of the superstitous audience.  In addition, Shakespeare sets the tone for the play by using the light vs. darkness and evil; he also presents the motif of moral choices and religious ideas.  The use of the witches  is effective with a character of such cupidity as Macbeth who succumbs easily to their seductive evil influence.  Unlike Banquo who is cautious in believing the witches

...But 'tis strange:/And oftentimes, to win us to our harm,/The instruments of darkness tell us truths,/Win us with honest trifles, to betray 's/In deepest consequence (I, iii,122-126).

Macbeth succumbs to the charm of political advancement:

If chance will have me King, why,/chance may crown me,/Without my stir (I.iii.144-146).

Another use of the witches and supernatural is in Shakespeare's motif of appearance vs. reality which runs throughout the play.  One such example is in the vision of the dagger. Is it a hallucination of Macbeth's or a vision sent by the witches?  At any rate, the supernatural controls the character of Macbeth and this is the purpose of the three witches.