Act III as the 'Gothic Centre' of Macbeth?

How the gothic nature of the play has been used to heighten the tragedy of Macbeth by the end of Act III.

• Morality. At the time of Shakespeare, King James I (England) was obsessed by the idea of witches and witchcraft. Extensive hunts and burnings of witches occured all over the country, and thousands of women were killed after being accused. It has been said that it was these 'Burning Times' that inspired Shakespeare to use the 'weird sisters'. Even if you do not follow the chirstian religion, you will more than likely adhere to the ten commandments. It was these Christian morals that sparked the witch hunts, as they were closely associated with the Devil.
• In Act III of Macbeth, the murder of Banquo is shocking, as initially we are introduced to him as being a friend of Macbeth. It highlights the downward spiral of Macbeth and his sanity, as he is clearly becoming paranoid and insecure.
• In previous scenes, it is clear that Macbeth is aware of the wrong in murdering. He is reluctant to kill Duncan, and is seen to be feeling the guilt of his crime. It is in act III, however, that his morality can be said to have decreased alot.
• Supernatural (and Witchcraft). The theme of witchcraft becomes prominent in the fifth scene of Act III. The three witches are meeting with Hecat, the goddess of witches. Hecat is angry at them for going above their station in seeking Macbeth, and would have been frightening for audiences in the time already obsessed with the idea of witches.
• The ghost of Banquo also appears to Macbeth, again drawing attention to the hallucinations he has (the dagger in Act II). This could further give evidences for Macbeth's unhealthy mental state, and possibly the idea that he has a moral conscience. Despite the fact he appears bloodthirsty and willing to kill again, the apparition of Banquo's ghost could hint at the remaining morals within Macbeth.