BOOK REVIEW / NONFICTION : A Look at the World Under the Big Top : NIGHT AFTER NIGHT <i> by Diana Starr Cooper</i> ; Island Press $18, 192 pages

The last time I went to a circus, I was 8 and I was thrilled. As an adult, if I thought about circuses at all, I assumed that they were places where people did uncomfortable things with animals; enterprises on the aesthetic scale somewhere between tawdry and schlock.

Thanks to Diana Starr Cooper, I’ve learned that the 8-year-old’s beloved circus was more real than my adult notions.

Cooper’s “Night After Night” is an act-by-act account of a single performance of the Big Apple Circus. We meet the ringmaster, the performers and the animals. A traditional one-ring circus, the Big Apple Circus is international and egalitarian. It “has nothing to do with innocence or . . . make-believe, but with awareness, with the delight and the pain inherent in complete consciousness.”

“Night After Night” is a hymn to the virtuosity of circus animals and performers, but it is also a theory of how the circus fits in the world, how it exists for its audience and its performers.

In the circus, “there are myriad ways of living and moving in a human body. It turns out that some of us can turn inside out. . . . It turns out that some of us can fly.”

Cooper believes that the “Classical circus with its dedications and masteries stands gallantly, idiosyncratically opposed to any vision of life that divides creation--its races, ages, nationalities and religions, its species--into compartments where they are inaccessible to each other.” This is heady theorizing, and it is a tribute to Cooper’s skill that we come to share her views.

Cooper’s prose can be too lavish and sometimes a sentence goes on a phrase or two after it should have stopped. But as J.P. Sartre noted, the test of good prose is transparency and by this test, Cooper succeeds: We do see what she sees.

About elephants--”I have seen toddlers absolutely terrified at the sight, so nearby, of an elephant. They know elephants are big. This turns out to be the first and most important thing to know about elephants, and it’s interesting to discover how few adults realize this and how little they respect it.”

About camels, which--”give off an unmistakable air of only just barely doing what they do--an air of willful disorder only temporarily, and not quite, arranged.”

And horses--”What some people find passionately interesting about horses, other people fear: Their combined size and sensitivity; the sense of a consciousness both heightened and remote; what the old books used to call their ‘excitability in motion.’ ”

Although Cooper does justice to the human acts--clowns, aerialists, the contortionist who demonstrates that “deformity is a false, if terrifying, category”--she agrees with Ringmaster Paul Binder that “circus is the art form most closely involved with the relationship between animals and people.”

Given our deep confusions about animals, it is not surprising that we are confused about circus animals. Cooper tells of a child who wept when he saw the real, contented, circus elephants. He’d been told horror stories by his grandfather.

“I felt immensely sorry for this child who had been robbed of elephants,” Cooper says. “It seems to me that the grandfather had corrupted his grandson--had ruined (the child’s) ability to read the . . . living creatures before him. The lies about suffering were more compelling.”

We live in a time when a good many decent people seem to think that the most interesting thing about animals is their (real or imagined) suffering, when the distrust of the human animal is so great many believe other animals would be better off without us. “Night After Night” is a description of one place where human knowledge and animal virtuosity intersect. It is a brilliant, necessary book.