What an impressive painting!
Only Chagall could convey the delightfully frustrating tussle of the creative process and take spatial considerations to a higher level.
There is much to enjoy this painting. I think I should limit myself to a vertical integration and some wonderfully placed spatial planes.
The vertical integration begins at the top with a short blue line. Your eye then connects to another line above the shoulder. You then continue through the figure. You also can connect the verticals above the shoulder to a vertical at the bottom. Chagall offers you choices.
Now to the planes, and I will focus on the area near the hand with the glass. Do you see a small rectangle just to the left of the glass. Can you feel it being in front?
The other plane is just below his hand, actually it overlaps the hand. I hope you can sense different levels. Note also how the cup integrates or connects with the plane.
There is a lot going on in a Chagall painting, and I will continue in the next posting.