In contemporary art you can see ideas put to the test of realization. Richard Long is an artist who has tested the idea that what makes something art is the circumstances in which we encounter it.
To do this, he pushed art to the edge of disappearance, or of appearance, as he might say. He is famous for traveling to isolated places (from England, where he lives) and making arrays of indigenous materials on the landscape. He documents the configurations he makes by photographing them, often in such a way that the camera angle suggests they would not look coherent from any other viewpoint.
In a typical piece, Long went to a mountain valley and traced an ''X'' on a bed of stones, using slightly larger stones as his ''material.'' You can look at the photograph of this work and miss the configuration on the ground at first, because it is stones on stones. But if you have the curiosity to go on wondering why this apparently ''empty'' landscape photograph was taken, your eye will soon find the ''X.'' The photograph is something more than documentation. It is an image that signifies the moment when you spot a pattern you have previously overlooked.
Long contrives it that spotting the pattern will be a matter of recognizing that something has been done, something manipulated, in a landscape where at first it appeared only natural forces had been acting. Very few people ever see Long's land art firsthand. Its intelligibility, in a sense even its existence, is dependent upon the camera.
Even in an indoor installation such as ''Bluestone Circle,'' the self-effacing qualities of Long's art are apparent. In his land art, he often makes use of materials available at the site. In ''Bluestone Circle,'' he has accepted the shapes given his material by the quarrying process, rather than impressing his sensibility upon them by carving them, as a more traditional sculptor might have done.
The refusal to carve, which any viewer mindful of the history of sculpture will sense in Long's use of stone, is not artistic petulance. It signifies Long's insistence that we look hard at each specific thing he employs because no unit of material represents another. Carving is a traditional technique for making images in stone. From the way Long handles stone, we may infer that he understands representational sculpture as depleting the reality of both image and material. A stone sculpture of a man's head is not quite a man's head, no matter how realistic it may be, and the more convincing an image it is, the less it is a stone.
One by one, the units of stone in ''Bluestone Circle'' are just what they appear to be. Accumulated into a circular ensemble, they begin to look like fragments as well as whole elements, almost as if a circular slab of stone had been dropped on the floor and shattered. Here, as in the artist's works on the land, the array's definition as art is slight. Long has arranged the stone units carefully so that their configurations will have a resonance with the ancient stone dolmens and markers that interest him, and perhaps with architectural ruins, but will not suggest mundane associations such as a clock face. He gets us to sense the working of our own imagination by the simplest means: forming a ''circle'' with a collection of rigid, rectangular solids.