Victor Vasarely (1908-1997) is generally considered to be Op art's founding father. Op art is a form of visual art, most usually painting and printmaking, in which colours are composed and juxtaposed in such a way that an optical illusion is set up and the surface appears to be fluctuating. Vasarely was influenced by science, and from his knowledge of various theories of physics developed his own around the relationships of colour and form. He devised a formula in which a basic shape - the square - becomes the background of another geometric form contained within it; the number of colours and forms were limited, but their combinations could be infinite. He was a great believer in 'Art for All', believing he could produce easily affordable works of art by using industrial methods of production. He mass-produced silkscreened sheets of colour, die-cut shapes and used photography to produce low-cost, high-quality prints and relief sculptures, or 'multiples'.