Modern art refers to a new approach to art where it was no longer important to literally represent a subject (through painting or sculpture). Instead, artist started experimenting with new ways of seeing, with fresh ideas about the nature, materials and functions of art, often moving towards further abstraction. The years before the 1st world war, a creative explosion took place with fauvism, cubism, expressionism and futurism. World War I brought an end to this phase, but indicated the beginning of a number of anti-art movements, such as dada and the work of Marcel Duchamp, and of surrealism. Also, artist groups like de Stijl and Bauhaus were seminal in the development of new ideas about the interrelation of the arts, architecture, design and art education. Modern art was introduced to America during World War I when a number of the artists in the Montmartre and Montparnasse Quarters of Paris, France fled the War.