In April 1917 Marcel Duchamp submitted to the Society of Independent Artists exhibition in New York — whose rules stated that 'all entries shall be accepted' — a standard porcelain urinal he had bought from Mott Iron Works, signed 'R. Mutt 1917'. After a contentious vote the work was excluded from the exhibition. Duchamp, a founding member of the Society, announced his resignation and left.

Duchamp's move is this: for an object to be a work of art, it does not have to be hand-made, to display aesthetic quality, or to involve the artist's manual labour. The artist chooses an object, places it in a context (gallery, exhibition), and signs it — that act is the work. Duchamp called this class *readymade*; he had begun in 1913 with Bicycle Wheel, and reached the sharpest expression in 1917 with Fountain.

After the original urinal was lost, Duchamp from the 1950s on commissioned seventeen 'newly signed' replicas, distributing them to major museum collections. Today Tate Modern, MoMA, Pompidou, and Philadelphia each have a Fountain — but none of them has 'the original'. This is part of the point Duchamp meant: the hunt for 'originality' is not the question art is for.

The greater part of conceptual art, Pop Art, performance art, and contemporary art owes itself to this move. In a 2004 international art-world poll of 500 figures, *Fountain* was voted 'the most influential artwork of the twentieth century' — ahead of Picasso's *Demoiselles*.