The Corrupting Power of Unchecked Ambition. The main theme of Macbeth-the destruction wrought when ambition goes unchecked by moral constraints-finds its most powerful expression in the play's two main characters. Macbeth (full title The Tragedy of Macbeth) is a tragedy written by William Shakespeare, and is considered one of his darkest and most powerful works. Set in Scotland, the play illustrates the damaging physical and psychological effects...