What was M.C. Escher's research question?

M.C. Escher's research question revolved around the exploration of mathematical concepts and their artistic representation, particularly how to depict infinity, symmetry, and the interplay between two-dimensional and three-dimensional spaces. He was fascinated by tessellations, impossible constructions, and the relationships between objects and their reflections or transformations. Through his artwork, Escher sought to challenge perceptions of reality and create visual paradoxes that engage viewers in a deeper contemplation of space and form.