Ambition. Although he is encouraged by the Witches, Macbeth's true downfall is his own ambition. Lady Macbeth is as ambitious as her husband, encouraging him to commit murder to achieve their goals. Both Macbeths fail to see how their ambition makes them cross moral lines and will lead to their downfall.
The similarity between a story and a free verse poem is that they both don't need anything to rhyme in it. Both of them don't consist of meter or musical patterns.
