If hailed by the critics, exhibits of modern art have, all too often, bemused, bothered, and bewildered the average viewer. What the expert proclaims as a masterpiece is, in the eye of the ordinary beholder, merely a mess. This is particularly true in the case of nonrepresentational art, the subject of Oscar Mandel's contemplative yet controversial essay. To Mr. Mandel, such art is "minor art," whose greatest fault lies in "its failure to engage ... the moral interest." Mr. Mandel is Professor of Humanities at the California Institute of Technology and author of more than a dozen books, including A Definition of Tragedy and his two-volume Collected Plays, " I wear two hats," he commented recently."Under one hat I write on aesthetics and publish translations of plays of interest to specialists and presented with scholarly introductions and apparatus, and under the other I am a playwright, poet, and fabulist—what they call a "creative writer" nowadays." He describes his VQR essay as "a sort of pendant to an article entitled "Dissonant Music Sixty Years After, " which appeared in the South Atlantic Quarterly in 1973."