Marcel Duchamp, by introducing in 1917 a urinal as an object of art in a Parisian gallery, both conceptualized and relativised art by explicitly stating that beauty, or truth for that matter, is only in the eye of the beholder, and that the question of whether an object is a piece of art, or just a piece of junk, depends A) on the social context B) on our readiness to accept that context as a fitting environment for art. Contemporary history was to prove him right. Duchamps' “virginal” gesture – because to a true modernist no work of art can ever be compared to another – has since been repeated a million times in installations all over the world, the one more elaborate than the other. But in essence these installations only amount to illustrations of the thesis that it is the context, that is, to art wholly external factors, which determines whether or not an object is to be considered a piece of art. It follows that an unknown Rembrandt painting, covered in dust in a rural Flemish kitchen among other bric-a-brac, a priori is no more worth as art than the reproduction of the Gypsy girl shedding a shimmering tear next to it. If the Belgian peasant woman prefers it, it's a greater piece of art for her, and that's what matters.
http://www.alternativeright.com/main/blogs/untimely-observations/a-history-of-the-modern/(tl;dr any Part > any Composite)