The most influential artwork of the 20th century, according to a survey of 500 professionals in the art world, disappeared from view in 1917. More important to the field of art than any individual work by Warhol, Picasso, Emin or Hirst, it was likely thrown in the trash by the one person to photograph it. “Fountain” was never even displayed at an exhibition; in fact, it was hidden behind a partition — shielded from view — despite the fact that its creator was a board member of the Society of ...