Note the way in which Shakespeare plays with images such as these. Often he builds up a cluster of related images (as here, "plant," "growing," "grow," and "harvest") precisely in order to establish a sense of irony. In the next speeches, for example, the king first invests all those who deserve his thanks with "signs of nobleness, like stars." Only a few lines later, Macbeth, frustrated and angry at the news of Malcolm's investiture as Prince of Cumberland, breathes to himself the words "Stars! Hide your fires! Let not light see my black and deep desires" (50–51).
Here, the juxtaposition of images of starlight and the cancellation of starlight emphasizes the great opposition between the king and Macbeth and between good and evil, an opposition that is ironically reinforced by the king's final lines to Banquo, once more praising Macbeth. The phrase "peerless kinsman" gives added poignancy: The historical Macbeth was the cousin of Duncan, and his crime will not simply be regicide, but the willful destruction of the head of a family.
