Please explain this quote from Macbeth in detail:
O, never(65) Shall sun that morrow see!
Your face, my Thane, is as a book where men
May read strange matters. To beguile the time,
Look like the time; bear welcome in your eye,
Your hand, your tongue; look like the innocent flower,(70
But be the serpent under't. He that's coming
Must be provided for; and you shall put
This night's great business into my dispatch,
Which shall to all our nights and days to come
Give solely sovereign sway and masterdom.(75)
To begin with, this is Lady Macbeth talking to her husband. She begins by saying that Duncan will not live to see the next day. She warns him that his face can be "read" and he should hid his true feelings. He should welcome Duncan and not let on his true purpose. She says to look innocent while hiding his intention which is to kill the king. There is a double meaning in he "must be provided for". On one hand he must be welcomed as the king and given all the pomp and circumstance connected with being king. On the other hand she means he must die. She tells him to leave everything to her and she will arrange everything for him. Once the deed is done, they will rule Scotland as king and queen.
These words are uttered by Lady Macbeth in Act 1, Scene 5 when she instructs her husband, Macbeth, how to behave in front of king Duncan when he arrives at their home. Right before this quote begins, Macbeth says that the king plans to leave their home tomorrow, to which Lady Macbeth replies that that day shall never come ("O, never Shall sun that morrow see!"). This is so because they have both decided to kill Duncan, so that they could become the king and the queen of Scotland. After Lady Macbeth says that the king will not leave their home once he sets foot in their house, she tells her husband that others may understand his true intentions because his "face...is as a book where men may read strange matters." Therefore, he should conceal his secret ambition by pretending to be a great host, who will take care of Duncan and the guests, yet he must not forget about his plan to murder Duncan:
Bear welcome in your eye,
Your hand, your tongue; look like the innocent flower,
But be the serpent under't.
He must be duplicitous by pretending to be loyal to his king in public, yet secretly planning to kill him afterwards. Lady Macbeth continues by saying how the king must be taken care of ("He that's coming must be provided for..."), which means he must be welcomed appropriately, yet be killed when the right conditions are created for that. She assures Macbeth that she will take care of the whole plan and that their lives will change for the better that night.
One of the most prominent themes of the play can be observed here - appearance versus reality. Macbeth is instructed to appear welcoming and loyal, yet, his real intentions, awakened and backed by Lady Macbeth, are unscrupulous and evil.