Being there only momentarily

Maurice Blanchot, discussing the cave paintings at Lascaux, from his essay "The Birth of Art", found in Friendship:

Art would thus provide us with our only authentic date of birth: a date that is rather recent and necessarily indeterminate, even though the paintings of Lascaux seem to bring it still closer to us by the feeling of proximity with which the seduce us. Yet is it truly a feeling of proximity? Rather of presence or, more precisely, of apparition. Before these works are erased from the history of painting by the ruthless movement that brought them to the light of day, it is perhaps necessary to specify what it is that sets them apart: the impression they give of appearing, of being there only momentarily, drawn by the moment and for the moment, figures not nocturnal but rendered visible by the instantaneous opening of the night.

Does art, then, bring into focus that which recedes from us?--unconcealment?--revealing a shadowy presence, for a moment, of that moment when we first emerged? The sense that the Lascaux paintings give us, of being the birth of art, even they were not the earliest--is the sense that art is always present at the birth of itself? For literature to be art, it should just come into focus, or attempt to articulate something difficult, attempt to express the inexpressible, it should depict something just around the corner, just beyond perception?