What is the purpose of having an empty mind? Following your example, when I watch color, my eyes are not completely empty, but are full of this color, otherwise how could I see it?

You give example of a guru the trickster, who was putting their disciple further into their folly. Did the guru just point out to the student the potential absurdity of their preexisting beliefs, like 'following your logic one would arrive at an absurd conclusion', or outright con the student?

If con artists were defrauding people, would you just say that they benevolently force people to abandon their beliefs in order to be liberated from them?

I still don't understand what value the book is creating. What is it supposed to teach me? Would teaching anything at all defeat the purpose of having a mind free from all beliefs?