Wayne C. Booth begins his book - an examination of the relation of ethics to literary art - where he began his inquiry: in a staff room at the University of Chicago in 1963.

I am not certain whether Isaac Newton's possibly apocryphal apple actually bopped him on the head when it instigated his discovery of gravity. As for Booth, he was indisputably bopped when his single black colleague on the humanities staff got up and committed, as the author puts it, "an overt, serious, uncompromising act of ethical criticism."He could no longer teach "Huckleberry Finn," the colleague announced. Its treatment of Jim, however well meaning, was an insult to black people and a slighting of their history.

For a sophisticated, liberal, art-for-art's saker like Booth, that was as close as you could get to burnable heresy. Surely, anyone could see that "Huck Finn" was a Great Book, a classic, and that its genius refined its material particulars to a purity beyond all offense.

History shows, though, that even if you burn your heretics, you may learn some of what they have to teach. "The Company We Keep" is Booth's quarter-century exploration of the question raised for him that day.

On one level, it is a thoughtful and sensitive examination of how we receive literature and what it does to us.

On another level, it is an extensive account of the critical wars among assorted platoons of Nothing-But-ers: Literature is nothing but text, nothing but form, nothing but a reflection of society, nothing but points made in the service of one ideology or another.

Finally, it is a witty and disarming personal record of the author's shifting allegiances and certainties, of his wanderings around the battlefields, and of his emergence as a firm believer in the peace of the brave; insisting, among all these bellicose purists, upon "a radical critical pluralism."

A novel, a poem or a play invades and takes possession of us, and it must establish a relationship of trust, even a friendship. This may sound strange in the case of modernist and post-modernist work. Yet look, for example, at how whole heartedly we commit ourselves to Kafka, once we have broken through to each other. The friendship is there; the friend is in trouble. The distances and the reversals of modern writing at its best simply extend the meaning of what trust is.

Illustrating his notion of friendship, Booth contrasts Norman Mailer's "The Executioner's Song" with Anne Tyler's "Dinner at the Homesick Restaurant." The first, he says, takes a big subject - violence in America - but treats it in such a casually arbitrary blend of fact and fiction "that I never come to the point of trusting him (Mailer) as a friend."

By contrast, Tyler's scope could not be smaller, yet "I feel that she is giving me everything she's got, and she cares a great deal about what will become of me as I read." No better thing has been said about her.

If literature invades us, then it inevitably occupies an ethical territory. Booth imagines an extreme formalist or an extreme deconstructionist - extremes meet - commenting on "King Lear":

"It was nice pretending for a while that filial cruelty is a terrible thing, that old and helpless fathers should not be tortured. But of course that value is culturally relative. I need not take it into account in my appraisal of the play."

"The Company We Keep," in its report on our literary battlefields, ranges widely and sometimes densely. The density owes more to the critical thickets that have grown up over literary theory in the past decades, than to Booth's outlook, which is lively. He is a jack rabbit even when he gets lost from sight - at least to the general reader and this particular one.