FOUR YEARS AGO, in the 35th reunion book of the Harvard class of 1942, Monroe Engel gave the following account of himself: "I have continued to teach, write and take in various forms of nutrient." That, recounted in characteristic fashion, is indeed what he has done for most of the past quarter century. More specifically, he has taught creative writing at Harvard during those years and written creatively on his own. As a writer who teaches and a teacher who writes, Engel has lived on a plot of middle ground somewhere between his two professions. He has lived near Harvard for many years now, but never fully in it. By writing and living outside the University, he has taught as much by example as by rote.

Where he lives is a rambling wood frame house near the Loeb Drama Center. Built for a large family in a style now obsolete, the house seems a bit hollow without the four (now grown) children who used to live there or the students who meet there once a week to talk about creative writing. The comfortable, lived-in part is the back, where current fiction (Italian Folktales by Italo Calvino) and current periodicals (The Paris Review, the Nation) lie about and are read. This is where Monroe Engel teaches, writes and, one presumes, takes his sundry nutrients.

He talks easily, and with a gentle grace; Engel lists "conversation" among the things he enjoys on the dust jacket of his new book. He has a crinkly smile and offers it frequently. He is not jolly, but a modern and friendly version of courtly. Speaking about his years at Harvard, Engel downplays the difficulty of teaching fiction and writing it at the same time. Scheduling problems, mostly. Students make large and immediate demands on his time, whereas the writing can always be put off. Further, there are "certain similarities of energies" required of writing and teaching, and he says his supply sometimes runs down.

By and large, though, he enjoys the confluence of professions. He speaks affectionately, almost indulgently, of his students, genuinely sympathetic to the difficulties involved in becoming a writer. He is, in fact, well known for the care with which he reads student work, and even more for his judicious criticism--balanced between unhelpful praise and crippling discouragement. "Most students writing fiction are working harder at it and putting more of themselves into it than anything else they are doing," he says, with the implicit suggestion that many a fragile psyche has teetered on the precipice of his blue pencil.

Over the past two decades, he has seen considerable evolution in the subjects and styles of student writing. About ten years ago, for example, during the height of student political activism, Engel says students were much more "consciously literary" than they are now, producing more imitative work. "I had a sense then that students were reading to save their lives, reading with great intensity....The political nature of the time had something to do with it. There was a kind of urgency that there isn't now," he says. But since that tumultuous period, which he said had "the highest concentration of really fine writing," student work has become more varied. Part of the reason, he says, is a lack of commanding writers. He cites Saul Bellow, Walker Percy, Bernard Malamud, and the poets John Berryman and Robert Lowell as influential, but he says no single writer or school is dominant. "All the students I see have read quite a bit," he says, "but there are curiously few intersections among their reading." Besides a drift away from confessional stories, and "a great deal more comic writing," he can cite no widespread fads, interests or obsessions.

ONE SUBJECT Engel does not talk about with his creative writing classes is his own fiction. After graduations from Harvard in 1942 and the United States Army in 1945 (where he was a communications officer who landed on Omaha Beach three days after D-Day), Engel has been writing continually. He published his first novel, A Length of Rope, in 1952, followed it with The Vision of Nicholas Solon in 1959, and Voyager Belsky in 1962. In addition to the three novels there has been a book about Dickens, the result of his Ph.D dissertation, and an edited collection called The Uses of Literature. Nineteen years after the publication of his last novel, he has produced Fish, which will be appearing this month (Atheneum, $12.95).

Engel began Fish eight years ago, after a long, false start on another novel. As the time since the publication of his last book grew longer, he had decided merely to get started on something--a move contrary to the advice he's distributed over the years. "I did what I tell students not to do," he says. "I jumped in before I really knew what I was doing." But the pieces came together about a year ago, an event Engel remembers with a combination of elation and relief. "One of the great moments for me in recent years was that day when I realized what I knew I wanted to do, and started throwing away a couple of thousands of pages of manuscript."

Despite its gargantuan doomed predecessor--the thrown-away thousands of pages--Fish is a lean volume, just 217 pages. It concerns the narrator, a private school teacher named Karp by his parents but nicknamed Fish by his girlfriend, who tries to escape from a life of "vagueing," in the author's memorable verb. Through Fish, his pathetic girlfriend and her mysteriously ailing son, the book is a portrait of a peculiar American social stratum, the educated middle class--the people whose material needs are inevitably satisfied and whose spiritual needs go inexorably unmet. They are the people who keep psychologists busy and urban French restaurants profitable. Many live in Cambridge, most see the Sunday New York Times, all read books.

Engel writes in a dense, sinewy prose, an elegant and complicated architecture that is never overly complex for the narrator. From the wonderful opening sentence--an artful ramble redolent of neurosis--to Fish's oddly inspirational conclusion, Engel works with remarkable control. He tells us enough about the characters, but does not burden us with more than what Harry Karp would wish to say. He savors details but doesn't fawn on them.

His words meander the way people think; Engel does not edit Fish's mind too closely, so the prose is often demanding. Consider the following passage, Fish's reflections after he has described the various "zones" that make up Harvard Square: "I pause hard at the corner then, considering whether to cross over or turn back, aware already even here in the borderland between the two zones of a taint in the air of unclear appetite, of relentless and unfocused inclination to consumption."

Despite the potentially disruptive presence of repeated flashbacks, Fish moves with assurance and gather a subtle momentum. Part of Engel's confidence with the subject may come from familiarity--with the people, and also the locales. The bulk of the novel takes place in Cambridge, and the evocation of the Square and its ambience is one of the book's chief pleasures. Engel is a fierce Cambridge partisan and a familiar figure strolling its streets in the evening. He writes of Harvard Square as he would a favorite tattered piece of clothing, with an affectionate and knowing eye.

Talking now in his study, frequently interrupted by friends' congratulatory phone calls about the book, Engel offers broad but cautious hints of his newest project. For the first time in his career, Engel may deal with his characters' politics--a significant part of Engel's life but not thus far of his writing. It may even include students, but he's not saying for sure. Engel brightens perceptibly when the subject of his writing comes up; he doesn't really talk much about the work, yet he seems comfortable in its atmosphere, relaxed in the familiar grip of his profession. Writing and teaching may not come easily to him, but he has made up his mind about his life and he has found quietude in the certainty of his decision. "I'm 60 years old," says Monroe Engel, "I write fiction because that is what I do. By now, I teach for the same reason."