<i> Diary of a Yuppie</i> by Louis Auchincloss (Houghton Mifflin: $16.95; 215 pp.) : <i> Louis Auchincloss</i> by Christopher C. Dahl (Ungar: $16.95; 276 pp.)

In his survey of Louis Auchincloss’ work, Christopher Dahl shrewdly remarks that Auchincloss “may be at his best when he writes about the past,” and that for his “most acute commentaries on contemporary life, one must turn to his short stories.” This may explain why Auchincloss’ latest addition to his long list of fiction--a hasty count yields at least 28 previous volumes--is not only a novella but a deliberately Jamesian novella. On the very first page, the narrator, Robert Service, writes: “And just what is a journal? A novel with a narrator, ‘I’? Henry James disapproved of these; he said that they limited the tale to what the narrator could observe. The greater drama, according to him, was to see the observer observing.” True enough, and with both James and Auchincloss, the initiate learns quickly to distrust the observer’s view. Here again, one is warned (on the second page) when Service blithely continues that people know “more about themselves today than they did in Mr. James’ time--or at least they should. And they certainly know more about themselves than even their closest intimates know about them. Or again--they certainly should.”

Ah, but does Robert Service? What a splendidly Jamesian name for a ruthless, rising 32-year-old lawyer, a yuppie of yuppies. By the time he has finished telling his story, he has quite legally robbed his original law firm of some of its most talented partners; he has served some clients in ways that lead to a separation from his wife, Alice, and their two daughters; he has in different ways serviced women of two generations, and he has served himself with a liberal hand.

An English major at Columbia, Robert lards his account with quotations from the poets, and when, separated from Alice, his equal in literary background running her own small literary agency, Robert is introduced by Sylvia Sands, a public-relations specialist with ambitions equal to Robert’s, to Mrs. Ethelinda Low, a woman of great wealth, he automatically thinks of Proust’s Odette in “Swann’s Way.”

Without giving away the resolution of the story, I can at least say that in what some readers may consider a reasonable compromise, even a “happy” ending, the true Jamesian is finally rewarded--but only on the last page--with a genuine frisson of revelation and understands that Alice is a latter-day, legitimate cousin of Isabel Archer and Milly Theale.

On first reading, I felt that Auchincloss had struck a false note in having Ethelinda Low, rather than either Alice or Sylvia, explain to Robert the importance of saying “house” rather than “home,” “curtains” rather than “drapes,” “evening dress” rather than “formal.” On second reading, I realized that I myself am of Ethelinda’s generation. On third reading, I felt that with parents wise enough in the ways of the world to give their son his final school year at a prep school, even a third-rate one, before he entered Columbia, they should have performed this service, and actually would have. I reserve final judgment for a fourth reading.

Dahl’s study of Auchincloss offers a level-headed appraisal, more underwritten than it should be because Dahl remains so determinedly careful not to put forth too great claims for his subject that he may at times be doing him a disservice. It’s a tricky enough matter to judge a living writer, especially one like Auchincloss, who is advancing into a new phase of writing. If I were Auchincloss, I might genteelly grit my teeth on reading “This is not, of course, to say that Auchincloss is destined to become one of the major figures of twentieth-century American literature. He is not; but what he does he does well.”

Dahl provides both an excellent introduction for those who know little of Auchincloss’ work and an able commentary on what he has achieved in his “novels of manners,” if that is really something more than a convenient catch-all phrase. James could never have written Edith Wharton’s “Summer,” and neither James nor Wharton could, if living today, hit quite the tone of “Diary of a Yuppie.”