What is the main theme of Shakespeare's "Macbeth"?

The main theme of Shakespeare's "Macbeth" centers on the corrupting power of unchecked ambition. Throughout the play, Macbeth's desire for power drives him to commit heinous acts, including murder, which ultimately lead to his downfall. This ambition is initially spurred by the witches' prophecies, which ignite a latent desire within him to become king. As Macbeth ascends to power through treachery and deceit, he becomes increasingly paranoid and tyrannical, demonstrating how ambition, when left unchecked, can lead to moral corruption and a complete loss of humanity.

The play illustrates that ambition, rather than being a motivating force for good, can consume the individual, leading to disastrous consequences not just for the ambitious character but also for those around them. Thus, the theme serves as a cautionary tale about the dangers of pursuing one's desires at the expense of ethical considerations and the moral implications of one's actions.