The series is defined by an unmitigating adherence to one pictorial formula: the square. The optical effects Albers created—shimmering color contrasts and the illusion of receding and advancing planes—were meant not so much to deceive the eye as to challenge the viewer’s faculties of visual reception. This shift in emphasis from perception willed by the artist to reception engineered by the viewer is the philosophical root of the Homage to the Square series.