GR by R. Wald: Apple & Canopy Cover Explained

[paweld]

I have recently notice that I the book General Relativity by R. Wald has
quite strange cover. Do you have any idea what's the relation of
apple and canopy with GR?

 

[waht]

The table represents a flat euclidean space. The apple represents a curved space which is a model for gravity in GR. Incidentally, there is a story about Newton who was sitting by a tree and an apple fell down to the ground and it inspired Newton to develop the Newtonian theory of gravity.

 

[Jimmy Snyder]

The painting is "Les Belles Realites" by Magritte.