Joseph Kosuth work’s validity lies solely in its idea:

"Aesthetics are conceptually irrelevant to art. Art “lives” through influencing other art, not by existing as the physical residue of an artist’s ideas. (J. Kosuth quoted in “Art After Philosophy” 1969, reproduced in P. Osbourne, Conceptual Art, London 2002, p. 232)"

Representative of Kosuth’s contribution to one of the most important contemporary art movements of the twentieth century, another variation of Four Colors Four Words can be found in the Hirshhorn Museum and Sculpture Garden, Washington D.C.

https://www.widewalls.ch/joseph-kosuth-art-auctions/four-colors-four-words-blue-red-yellow-green-1966/ (12.10.2019)