A magazine I used to read once ran a competition for creative misprints. The prize went to a reader who transformed a stanza in The Rime of the Ancient Mariner by adding a single letter to a single word; in the doctored version, the Mariner was compared to

one, that on a lonesome road
Doth walk in fear and dread,
And having once turned round walks on
And turns no more his head;
Because he knows, a frightful friend
Doth close behind him tread.

Ah yes, many of us will know what it is to be pursued by a frightful friend. Friendship can be a complicated phenomenon.

Few writers are better equipped to examine its complexities than Joseph Epstein. He has established himself, in both his essays and his stories, as a notably shrewd observer of men and manners, at once subtle and down to earth. His humor rests on a strong sense of how inconsistent people can be (and how comically consistent, too). He takes long views, but he is alert to short-term social change.

All these qualities are apparent in his new book, Friendship: An Exposé, but so is a more specific feeling for friendship itself. He is thoroughly at home with his subject—its gradations, its satisfactions, its paradoxes, its disappointments—and though he is widely read in the literature of friendship, from Aristotle and Montaigne to recent sociology, much of his best material draws on his own experience.

He certainly turns out to have (or have had) an impressive range of friendships on which to base his conclusions. His pages are littered with reminiscences of lunches, drinks, reunions, get-togethers, all convened in the name of amity. When he once remarked in the course of a talk that he had seventy-five or so friends, a lady in the audience said that she found it an almost unbelievably high number, but one suspects that it was an understatement.

One also wonders how he has managed to find time for them all. He himself feels that he has been saved by geography. The United States is a big country: If all his friends lived within easy reach in Chicago, he “might get no work done whatever, but go under, drowned in waves of friendship.” But distance can only provide a limited amount of protection. Epstein has a regular e-mail correspondent, a retired professor in Carolina, who can initiate up to four or five exchanges a day. The thought of reading five messages a day, let alone replying to them, would be enough to make some of us wilt; even Epstein admits that his replies “sometimes border on the terse.” But he finds his correspondent sympathetic, and he soldiers on.

There is a certain incongruity here. The book’s subtitle—An Exposé—suggests that we might be in for a display of disenchantment, even debunking, and Epstein tells us that he began writing it in a mood of dissatisfaction with “the standard idealization of friends.” Nor does he have any difficulty citing examples—some amusing, some sad —of friendships that have come to grief or simply fizzled out. But such failures by no means set the main tenor of the book. For all his awareness of the pitfalls, Epstein turns out to be far more concerned with the positive good that friendship confers.

Perhaps nothing indicates the value he sets on friendship more strikingly than the fact, as he tells us, that he has friends across the political spectrum. It is true that he makes it pretty clear that that doesn’t really include the extremes of the spectrum; he also adds the qualification: “I prefer a friend whose personality is not dominated by his politics.” But I still wish—if only so that I could learn from him—that he had said more about this whole thorny subject. I, too, aspire not to let politics interfere with friendship, where possible, but I seem to find it a more difficult trick to pull off than Epstein does. Too many people, in my experience, insist on thrusting their political opinions at you uninvited—vehement opinions, with which they take it for granted you’ll agree. Your only option, if you are not to start an argument, is to say as little as possible, and while friendship can survive under such circumstances, it is generally only in a curtailed and uncomfortable fashion.

And then there is sex. Aristotle thought that friendship was asexual in nature, and Epstein concurs. This seems to me unduly restrictive. It doesn’t allow for the whole tradition of the amitié amoureuse, and there are surely countless other friendships which, without being positively amorous, have a tinge of romance or sexual attraction. What Epstein is chiefly arguing against, however, is the Freudian assumption that all friendship has a sexual basis—that male friendships are essentially homoerotic, and so forth. Here, at this hour in the day, most of us are likely to go along with him. And when he comes to consider friendships—successful friendships—between men and women in general, he is at his best.

He begins with some classic examples drawn from the past: Dr. Johnson and Mrs. Thrale, for instance. But such happy attachments were on the whole confined to the privileged few. One of the great advances in life in recent generations is that there is now far more scope than there used to be for what sociologists call “cross-sex friendship” (Epstein winces at the phrase, too, but it saves time), and he goes on to describe some of his own friendships with women, friendships which might well not have been possible under an older social dispensation. The brief sketches he gives are touching and sometimes humorous, but the adjective they most merit is “civilized.”

Before he gets round to cross-sex friendship, he devotes separate chapters to women as friends and men as friends. The chapter on women is rather disappointing. It is not that one necessarily disagrees with the claims he makes for women’s superior capacity for friendship, or for their greater sensitivity. But his tone is often uncharacteristically bland, and you feel that in other contexts he wouldn’t quote some of the authorities he cites with quite such a straight face—the novelist Sue Limb, for example, who opines that at the heart of most female friendships is “a mixture of sympathy and instruction: of a loving heart and a shrewd eye.” Perhaps, but is that the best way of putting it?

When he moves on to consider men, it looks at first as though he is going to paint an even more exaggerated picture. When men talk about women, he says, “they either (1) complain about them or (2) exclaim how they wouldn’t at all mind bonking them. Broads. Go figure. Next subject.” At this point, you begin to suspect that he is teasing, indulging in a little outright parody. And then he turns in his tracks and admits that he seems to have been making out men to be “louts if not savages,” and women to be “little saints of sensitivity.” Neither suggestion, he adds, is strictly true, and he proceeds, in the pages that follow, to deliver a far more balanced and nuanced verdict.

It is true that at the end of the chapter on cross-sex friendship women are still awarded the palm for sensitivity, but in a manner that commands ready assent. Epstein rounds off his argument by quoting a character in Elizabeth Gaskell’s novel Wives and Daughters, Lady Cumnor, who observes that “You men concern yourself with the eternal verities; we women are content to ponder the petty things in life.” One of Lady Cumnor’s most attractive qualities, as Epstein makes clear, is the lightness of her irony.

For a relatively short book, Friendship packs in a great deal. The themes which Epstein addresses range from broken friendships to inequality in friendship, from the shaping power of technology to the tug of war between traditional male friendship and modern family life. In each case, he raises the most relevant questions and weighs the most significant views. But you never get a sense of him dutifully ticking off topics. He writes in a flowing essayistic style, which enables him to weave in anecdotes, pen-portraits, and whatever else takes his fancy.

His examples are unhackneyed, too. Discussing the problems that can be created by disparities in status, he offers a ringside view of the falling-out between Saul Bellow and the sociologist Edward Shils, and recounts the fascinating story of the cooling friendship between Chief Justice Warren Burger and his Supreme Court colleague Harry Blackmun. And he is a master of the clinching quotation. It is one thing to suggest that good talkers will do even better if they are also good listeners. It is quite another to summon up Max Beerbohm, recalling one of the qualities which made the English critic Desmond McCarthy such a popular conversationalist: “He was a great user of that beguiling phrase, ‘And tell me.’”

Epstein has previously written sparkling studies of envy and snobbery. Somewhat against the odds, he manages to make Friendship every bit as entertaining. But the really impressive thing is that he does so without diminishing his subject or overplaying its satirical possibilities. At one point he quotes Dr. Johnson’s words on friendship—“life has no pleasure higher or nobler”—and you feel that he’s entitled to.