Still Life with Spherical Mirror 1934

Here's a still life of a sculpture of a bird, a book, and a reflective sphere by M.C. Escher. I’m trying to imagine Escher’s experience as he was making this. Did he set this up? How long did it take to get the drawing exactly right? I bet he spent a long time trying to figure out the curvature of the sphere. The shading is so exact, it's mind-boggling. I want to know what he was thinking about when he included himself in the reflection in the sphere? It's like a painting within a painting. You can see Escher sitting at his desk drawing in a slightly distorted way. The sphere distorts the world around it, and the way Escher has rendered the highlights is almost like another kind of mark-making. Escher takes the still life and makes it into something so weird, a strange reflection, which is what so many artists are after.