'Let not see my black and deep desires.' How does this portray treachery in Macbeth's character in Act 1 Scene 4?

To begin with, Macbeth's desires are expressed as 'black'. From 'black', connotations of darkness can be received. In general if someone is doing something in the dark, it could be said that they are doing it sneakily. Macbeth's desires, in this case, are sneaky and if he has the need to hide these desires, then inside he knows what he would like is not good and that he might not be able to fulfill these desires without doing something bad.

From the word 'black', evil connotations can also be received as the colour 'black' is generally perceived as negative. The idea of these desires seeming evil could foreshadow further into the book, when he kills the king in an attempt to gain the throne. His desires at this point are maybe to become king but as they are expressed as 'black', they are evil desires as he can only become king by doing treachery.

In support of this 'evil' side to Macbeth, he says in scene 3, 'So foul and fair a day I have not seen'. The witches similarly chant in scene 1, 'fair is foul and foul is fair.'. The way in which Macbeth copies the witches, could show that he might copy them in the future and as witches kill to get what they want ('killing swine'), Macbeth could also kill to get what he wants and commit treachery.