Walter Benjamin

...the unique value of the "authentic" work of art has its basis in ritual, the location of its original use value.
...To an ever greater degree the work of art reproduced becomes the work of art designed for reproducibility.
...but the instant the criterion of authenticity ceases to be applicable to artistic production, the total function of art is reversed. Instead of being based on ritual, it begins to be based on another practice - politics.

Works of art are received and valued on different planes. Two polar types stand out: with one, the accent is on the cult value; with the other, on the exhibition value of the work. Artistic production begins with ceremonial objects destined to serve in a cult. One may assume that what mattered was their existence, not their being on view. The elk portrayed by the man of the Stone Age on the walls of his cave was an instrument of magic. He did expose it to his fellow men, but in the main it was meant for the spirits. Today the cult value would seem to demand that the work of art remain hidden. Certain statues of gods are accessible only to the priest in the cella; certain Madonnas remain covered nearly all year round; certain sculptures on medieval cathedrals are invisible to the spectator on the ground level. With the emancipation of the various art practices from ritual go increasing opportunities for the exhibition of their products. It is easier to exhibit a portrait bust that can be sent here and there than to exhibit the statue of a divinity that has its fixed place in the interior of a temple. The same holds for the painting as against the mosaic or fresco that preceded it. ...

With the different methods of technical reproduction of a work of art, its fitness for exhibition increased to such an extent that the quantitative shift between its two poles turned into a qualitative transformation of its nature. This is comparable to the situation of the work of art in prehistoric times when, by the absolute emphasis on its cult value, it was, first and foremost, an instrument of magic. Only later did it come to be recognized as a work of art. In the same way today, by the absolute emphasis on its exhibition value the work of art becomes a creation with entirely new functions, among which the one we are conscious of, the artistic function, later may be recognized as incidental. ...

Excerpted from his essay The Work of Art in the Age of Mechanical Reproduction (1928?) reprinted in Illuminations Schocken Books 62 Cooper Square NYC 10003