NONFICTION : WHO NEEDS THEATRE? by Robert Brustein (Atlantic Monthly: $18.95; 336 pp.).

“Who Needs Theatre?” is a collection of essays written between 1980 and 1986 by Robert Brustein, drama critic of The New Republic and artistic director of the American Repertory Theatre at Harvard. Learning, intelligence and a passionate commitment to the theater are everywhere apparent in these pages. But curious to say of such a devotee as Brustein, his essays are of the greatest value when he is most detached in his approach. They tend to ride off the rails into a no man’s land of misapprehension just when he is most involved, personally or intellectually, with what he observes and discusses. Thus, his pieces on the meaning of Lillian Hellman’s anger, or the essentially rhetorical difficulties underlying the South African political drama “Born in the R.S.A.” are cool, incisive and integrated in subject and argument. But his puffery for his former student Christopher Durang’s “The Marriage of Bette and Boo,” a jejeune broadside at modern American family life using TV sitcom characterizations as its blunt instruments of satire, is embarrassing.

His panegyric to Marsha Norman’s “Night Mother,” which he first produced, is positively loopy; he sees this attentuated suicide drama as an accretion of details that is Checkhovian in its beauty of form; the night I saw it the man in front of me, after having watched the protagonist fill candy dishes and write shopping lists all evening, jumped up from his seat and said, “She should have shot herself an hour ago,” thus hitting the nail Brustein doesn’t even seem to know exists.

His review of “Sunday in the Park With Geoge” is the only truly fine one on this work I have seen; his reportorial skils accurately describe what is on the stage, his critical skills determine precisely its lack of aesthetic cohesion.

The same faculties desert him as he tells us of Robert Wilson’s “Einstein on the Beach.” His considerable praise is imposed on the work, not discovered from his analysis of it. We can’t take his judgment of the piece seriously, because he can’t describe it in a way that convinces us that he or anyone else could know what it is. He can only give an account of various protracted, inchoate scenes, of indeterminate significance. By presenting no realistic intellectual basis for his encomium, he renders it spurious. So the book goes, veering back and forth between insight and imperception.

If you are interested in what ideas a leading light of serious American theater has been promulgating, for good and ill, Brustein’s “Who Needs Theatre?” is definitely for you.