What's a classic ?

This question is an academic, a worn out, a trite one. But it gets an unexpected relief if you consider the proliferation of this term today, for all sorts of things and not only for artistic and literary works of Louis XIV classicism. It is from that point of view that the set out here ideas are written down.These thoughts do not aspire to anything final : they give the state of the art of a collective current research, based on how the works are received. It seems to be not very relevant to give an aesthetic a priori definition of classics. It is on the contrary the cultural institution, especially literary institution and school apparatus which generates, for setting up models it needs, a canonial corpus, even if it means reorganizing components so as to give an image of æsthetic coherence where prevailed diversity, nay contradiction. So is established the value, which raises the classics, beyond the classicism, in exchanges values.