"The event that made conceivable the realization that it was possible to 'speak another language' and still make sense in art was marcel Duchamps' first unassigned readymade. With the unassisted readymade, art changed its focus trom the form of the language to what was being said. Which means that it changed the nature of art from a question of morphology to a question of function. This change - one from 'appearance' to 'conception' - was the beginning of 'modern art' and the beginning of 'conceptual art'. "
- Peter Osborne

Source: Osborne, Peter. 2002. Conceptual Art. p. 13. London: Phaidon Press.