Answer:
Neuroscience and Psychology. The scientific study of the brain is indispensable to the scientific study of the mind. Although neuroscience and psychology focus on different domains, neuroscience deals with the realm of physical properties, while psychology deals with the more abstract realm of the mental.
The witches are the ones who give Macbeth the prophecy that he will one day become king, that Banquo with father kings, and that Macbeth can not be killed by anyone born of woman. These set off Macbeth's entire journey in the play and motivate him to kill the king, kill Banquo, and ultimately lead to his downfall.