Lucas: We also wanted to have a scene where Vader goes and bows before the Force and the Force picks him up and tells him that he better go out and get that crystal… But it’s not the Force personified; it’s on the verge of personification. Maybe it’s a shadow or something.
Alan Dean Foster: The ultimate…
Lucas: It’s the ultimate evil. It’s the devil.
In a way this has come back in Vader’s prayer to the immortal gods of the Sith.