Three Spheres III, 1946

Escher was particularly intrigued by reflections and by the concept of a sphere acting as a mirror. Here, the central sphere that reflects Escher at work is flanked by one, at left, filled with water, and at right,   by another opaque sphere. All three spheres are reflected in the polished surface on which  they rest. The spheres at right and left are reflected in the center sphere. Finally, the entire composition is seen as the drawing on the paper reflected in the central sphere.