The seminal 1965 exhibition at the Museum of Modern Art, The Responsive Eye, provided many viewers with their first exposure to what would become to be called ‘Op Art.’ The scale of the show brought to the fore an international gathering of artists who, individually and collectively, were exploring new theories of visual perception. Perhaps ‘new’ is not quite the word as many of these concepts were born in the 19th century by a diverse group of theorists ranging from Johan