What are the main themes explored in Shakespeare's Macbeth?

Shakespearean themes can quite often easily be explored through the concept of a thematic dichotomy. A dichotomy is the construction of opposing ideas presented through the narrative to convey the writer's themes and intended message. Basic thematic dichotomies that Shakespeare constructs include his exploration of good and evil, as well as the clear distinction between power and powerlessness in Macbeth. In Shakespeare's works, individual characters more often than not symbolise one half of a dichotomy and are a good way to explore any themes. For example, Macbeth and Lady Macbeth are clear halves of the power and powerlessness and are a good basis for discussing this theme. This also gives an avenue into further discussion to do with character questions.
When trying to identify further thematic dichotomies, this approach of characters and clear 'character foils' - opposing or contrary individuals - is a useful technique in the context of Macbeth. Developing any thematic answer beyond a basic level can involve identifying any flaws to a clear distinction between characters, looking at parallels, and using similarities to explore Shakespeare's dichotomies on a less literal level, but more as a vehicle for demonstrating the vitiation of reality and certainties within it.