In Act IV, Scene 1, what news does Lennox bring to Macbeth, and how does Macbeth plan to change his behavior in response to this news in Shakespeare's Macbeth?
(i.e. What is Macbeth's resolve at the end of this scene, and how do his plans differ from some previous actions?)
Lennox tells Macbeth that Macduff has fled to England. Earlier in the scene, when the Weird Sisters showed Macbeth the apparitions, the first one told Macbeth to beware of Macduff, so Macbeth vowed that Macduff should not live. When the next vision told Macbeth that no man born of woman could harm Macbeth, he still said of Macduff, "Thou shalt not live!" With Macduff gone, Macbeth does not have access to him to kill him, so Macbeth says he will, "...give to the edge o' the sword/ His wife, his babes, and all unfortunate souls/ That trace him in his line." Macbeth will send murderers to Macduff's castle at Fife and kill Macduff's family since he can't kill Macduff. When he sent murderers to kill Banquo, he told his wife to be "...innocent of the knowledge....til thou applaud the deed," as though he were proud of the plan he concocted. This time, he will not hesitate, he will not come up with a clever plan to surprise his target, he will just get the job done. This shows us how cold-blooded, determined, and paranoid Macbeth has become. He no longer needs help from his wife like he did when he killed Duncan, in fact, she is useless since she has gone insane.
In Act IV, Scene 1, Lennox arrives after the witches to whom Macbeth has spoken have disappeared. In answer to Macbeth's query about the whereabouts of these witches, Lennox replies that he has not seen them. But, he informs Macbeth that two or three men have come by with the news that Macduff has fled to England.
When he is informed that Macduff has fled to England, Macbeth demonstrates that he has descended further into evil. For, whereas earlier when he has first heard the predictions of the weird sisters, Macbeth has considered allowing fate to determine what happens.
If chance will have me King, why, chance may crown me,
Without my stir. (1.3.143-144)
Now, having just been shown by these witches a procession of eight crowned kings followed by an image of Banquo at the end of the line, Macbeth recalls also their earlier prediction to Banquo. He, therefore, decides that the "flighty purpose" (fleeting plan) is never fulfilled unless it is carried out at once. He will act upon eliminating Macduff's wife, and "all the unfortunate souls/that trace him in his line" (4.1.158).
This peremptory act of Macbeth's, in contrast to his earlier hesitation, suggests his continuing descent into evil. These murderous attacks upon Lady Macduff and her children as a sort of retribution against Macduff's future indicate the ways in which Macbeth's imagination moves "on a wild and violent sea" (4.2.21).