In a piece written for the Session on the Creative Act, held in Houstan, Texas in 1957, Marcel Duchamp considers the role of the viewer in art.  He believes that the artist is like a medium who "seeks his way out of a clearing" with no conciousness…about what he is doing or why he is doing it".   Therefore, what ultimately determines a work of art’s meaning and importance within art history is not the intent of the artist, but rather what the viewer interprets that intent to be.  In Duchamp’s view,  a work of art is not made soley by the artist.  Instead, it is a colloboration between the artist and viewer in which "the spectator brings the work in contact with the external world by deciphering and interpreting its inner qualification and thus adds his contribution to the creative act". 

Click the link to download a PDF of Duchamp’s article.