The principal theme of the play is the corrupting force of ambition. The theme follows the Ancient Greek concept of hubris,—a protagonist’s overreaching pride brings him from a position of strength to one of humility in a tragic and typically irredeemable fall.

The play begins with Macbeth in a position of strength. He has won a great battle, enjoys the love of his king, and has been rewarded with a noble title—in sum, he has used his ambition for the benefit of his country and liege lord. For most men, this would be enough. But the witches’ prophecy changes everything. The idea of himself as king takes root in Macbeth’s mind, growing until he can no longer think of anything else. Now, his ambition takes on a darker cast. Lady Macbeth’s ambition matches that of her husband and together they conspire to take the throne through violent, sinful deeds. Their ambition erases all moral boundaries until Macbeth and Lady Macbeth are entirely corrupted.

But this cannot last. Macbeth’s ambition soon turns to paranoia and hysteria. By the final act of the play, Macbeth has achieved his ambition and become king. But it has come at a great cost: In order to achieve his goal, he has murdered a king, friends, and an innocent woman and children.