There are many themes in Macbeth but one of the main ones is greed and ambition and how they can destroy someone. Macbeth has what has been termed a 'tragic flaw' in that his greed for the throne spurs him into murder; a murder which later causes immense guilt. This guilts also affects Lady Macbeth, who has encouraged him, and eventually causes her suicide. Macbeth has been weak in being persuaded and he pays a terrible price. The murder of Duncan the King sets in motion a chain of events that cannot be stopped.
Shakespeare also looks at the idea of superstition as Macbeth is convinced that he wiill have the throne because of the witches' prophecy. However, he has misinterpreted what they said, as he discovers later. Macbeth is only too willing to accrept his version and use it as an excuse for murder.