After Macbeth returns from Duncan's chamber covered in blood, he is visibly shaken and emotionally disturbed. Macbeth instantly regrets committing regicide and experiences extreme guilt for his actions. In contrast, Lady Macbeth remains composed and is upset that her husband is behaving like a frightened, sensitive woman.

Lady Macbeth criticizes her husband for refusing to reenter Duncan's chamber and is forced to place the daggers near the sleeping guards herself. When Lady Macbeth returns from Duncan's chamber, Macbeth once again laments his actions by saying, "Will all great Neptune’s ocean wash this blood / Clean from my hand?" (Shakespeare, 2.2.60). Unlike her guilt-ridden husband, Lady Macbeth boldly accepts responsibility for Duncan's death and shows no remorse by saying,

My hands are of your color, but I shame
To wear a heart so white.

In this quote, Lady Macbeth is acknowledging that her hands are also (metaphorically) covered with Duncan's blood, signifying her own responsibility for this terrible crime. In the second half of the quote, Lady Macbeth is ridiculing her husband for acting sensitive and regretting his actions. By saying that she "shame to wear a heart so white," Lady Macbeth is saying that she would be embarrassed to have a pale, weak heart. While the color red is associated with guilt and crime, the color white represents purity and innocence. At this point in the play, Lady Macbeth has already asked evil spirits to fill her soul with cruelty and remains callous following the murder. Her comment is yet another shot at Macbeth's masculinity as she attempts to motivate him to remain calm and carry out their plan.

Since Shakespeare chose not to show King Duncan being murdered in his bed, he wanted to emphasize the reality and horror of the deed by showing both Macbeth and his wife with bloody hands. The purpose of all the looking at hands, showing of hands, and talking about hands is to call the attention of the audience to all the blood. First Macbeth says:

What hands are here? Ha, they pluck out mine eyes!
Will all great Neptune's ocean wash this blood
Clean from my hand? No, this my hand will rather
The multitudinous seas incarnadine,
Making the green one red.

Then his wife replies directly to this statement:

My hands are of your color, but I shame
To wear a heart so white.

They are both making a display of their bloody hands in order to produce a strong emotional effect on the audience. Their hands are, in effect, proof of the commission of a terribly bloody murder as well as a proof of their guilty partnership.

When Lady Macbeth says, "...but I shame / To wear a heart so white," she means, "I would be ashamed to wear a heart so white," i.e., I would be ashamed to be such a coward. She is telling her husband to stop bemoaning the crime he has committed. She is continually manipulating him by questioning his courage and manhood. She knows that this is only the beginning. They will have to keep their nerve in the morning when the King's body is discovered and there is pandemonium throughout the castle.

It seems that both husband and wife are "suiting the action to the word," as Hamlet (speaking for Shakespeare) tells the actors in that play. Macbeth and his wife not only display their bloody hands but get more blood on themselves while speaking the above-quoted lines. Macbeth probably would drag his fingers across his brow and eyes as he said, "What hands are here? Ha, they pluck out mine eyes." The audience would not know for a few moments whether Macbeth had actually, like Oedipus, actually torn his eyes out. His fingers would leave trails of blood all the way down his cheeks. Then when Lady Macbeth countered that she would "shame to wear a heart so white," she would wipe one hand across her white gown with the word "shame" and the other hand across the other side of the gown with the word "white."

Shakespeare must have wanted to use lots of blood in this scene to represent the terrible murder and to make up for the fact that he did not actually show the it being committed. He may have considered inserting a scene in which Macbeth stole into the King's bedchamber and stabbed the old man to death, but such a scene would obviously be hard to enact. And there would be no opportunity for Shakespeare's poetic dialogue. It would be a sort of dumb show and not emotionally effective like the scene in which Macbeth and his wife are smearing themselves with the King's blood. Both Macbeth and his wife are elsewhere given plenty of lines in which to describe what went on inside the King's bedchamber. For example:

MACBETH:

There's one did laugh in's sleep, and one cried,
“Murder!”
That they did wake each other: I stood and heard them:
But they did say their prayers and address'd them
Again to sleep.

What is the significance of the quote from Macbeth: "My hands are of your color?"

Macbeth has just committed the murder of Duncan, and it has upset him so much that he has carried the murder weapons out of the room rather than placing them on the chamberlains that he and Lady Macbeth intend to frame for the crime. When she tells him to return the daggers, he refuses, saying,

I'll go no more.
I am afraid to think what I have done.
Look on 't again I dare not (2.2.65–67).

He admits to his fear; he does not even want to think about the terrible thing he has done. As a result, his wife feels that he is being a coward. When she says that it is "the eye of childhood / That fears a painted devil," she insults her husband and compares him to a child, someone who is afraid of things that aren't really dangerous at all (2.2.70–71). He feels so guilty, however, that he feels that the blood on his hands will make the

[. . .] multitudinous seas incarnadine,
Making the green one red (2.2.80–81).

He refers to the color of the blood on his hands. When Lady Macbeth returns, having taking the daggers back, she says,

My hands are of your color, but I shame
To wear a heart so white (2.2.82–83).

In other words, her hands are now as red and bloody as Macbeth's—she touched the daggers and smeared the grooms with Duncan's blood—but she says that she would be ashamed if her heart were as "white" as her husband's; she insults him again, referring to his cowardice.

It is always interesting to me that Lady Macbeth could not commit the actual murder herself; early in the scene, when she is alone on stage, she says of Duncan,

Had he not resembled
My father as he slept, I had done't (2.2.16–17).

Lady Macbeth, then, did not have the wherewithal or fortitude to commit the murder on her own, but she is quite willing to berate and chastise her husband, who did do the terrible thing, for his unwillingness to return to the scene of the crime. This is pretty ironic, isn't it? If she's so strong and brave, then why couldn't she kill Duncan? Her selective bravery and bravado seems to indicate that her strength could falter later, and it does.