Explain briefly act 1 scene 4 and the theme involved.

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gbeatty eNotes educator| Certified Educator

There's a good and pretty brief summary of that scene found in the enotes study guide to Macbeth (see the Summary and Analysis section):

You could also put it this way: Duncan names Malcolm as his heir, and this means that Macbeth will have to kill him for the prophecy to come true.