http://www.understandingduchamp.com/
Marcel Duchamp, creator of 'The Fountain' he created a series of 'ready mades' by altering them slightly. He goes on to justify the use of ready mades as he says it does not matter if the piece was not made by whoever, it is the fact that he chose it himself and decided to use it himself. The website states: At the time nobody understood what Duchamp was talking about but 50 years later everyday objects would be common place in art.
The people who did in-fact use the everyday objects are the postmodernists we know today.