‘Enemies of Promise” (University of Chicago Press, 288 pages, $17), Cyril Connolly’s three-part summary of modernist literature, the perils of the writer’s life, and the travails of his own, was written over a hot July and August of 1938. Not a bad effort from a man who often described himself as lazy and “indefinitely promising.” Like many lazy people, he always wrote well under the gun — and everyone, then, was under the gun.

“Enemies of Promise” was first published the September week Neville Chamberlain flew to Munich. It was a pretty bad time to introduce a book on how to make it as a writer in England or anywhere in Europe. There was the biggest enemy, one Connolly mentions often, if only in the background: a looming war, which surprised no one except England’s prime minister, and which threatened the end of civilization as they knew it. Not only did a young writer in 1938 face the problem of what Connolly termed “the chaotic liquidation of the West,” there was also a high probability of being liquidated oneself. Henry Green, the novelist and Connolly’s junior classmate at Eton, caught the mood with affecting understatement, “Surely it would be asking much to pretend one has a chance to live.”

Looking back through this anniversary reprint from the safety of 70 years, it’s worth keeping in mind the contrast between the immediacy of that generation’s well-grounded anxieties and our own literary generation’s thoroughly mediated, if no less anxious, visions of the collapse of civilization. Connolly’s recommended response was to keep writing, “as if it were the illusions of humanism that are real and the realities of nihilism that prove a nightmare.” This counsel sounds more comforting than it turns out to be on closer inspection: Know reality and then ignore it, but never so much as to forget it, and never so much that it might later overwhelm you. Now try this on your own, but don’t get your terms mixed up or you’re in trouble. More than Connolly’s stated intent, to advise novelists on “how to write a book which lasts ten years,” this taste for shifting the ground beneath the reader’s feet constitutes the enduring charm of “Enemies,” and also its continued relevance.

Connolly had a great gift for self-consuming paradoxes. He begins with an account of the summer forest fires near his country cottage in the south of France: “We fight them by starting little manageable blazes which burn a strip to ashes before the main conflagration has time to arrive.” By book’s end, the light atmospheric detail has turned into an emblem of what he means by literary criticism — by which he also means self-criticism, fighting fire with fire.

Take the book’s second section, an enemies list cheekily drawn up in “bolshie” fashion, then ornamented with ironic neoclassical allusions to an 18th-century pastoral poem about a rye field choked by weeds. There is an unstable balance between politics and classical literature, high and low. In the shadow of the war, the enemies Connolly focuses on most intently can seem largely trivial, though they are all still with us. There is history, but there’s also daily life within history. Sometimes the forest fire is sparked by a match in the woods rather than a bomb. Sometimes the writer lights the match.

The ordinary conflagrations that threaten to consume a life, or a writer’s best years, can be fought off with modest eruptions of what Connolly didn’t know to call “kvetching”: Literary journalism is “a whole time job on a half-time salary,” he writes, that benefits only those who “suffer from psychological sloth.” Editors are vampires. This is self-satire — Connolly was a frequent reviewer for the Times Literary Supplement and later founded and edited the literary journal Horizon. Direct political writing is bad for you, he argues, but the refusal to try politics is no less a symptom of weakness: “the writer whose stomach cannot assimilate with genius the starch and acid of contemporary politics had better turn down his plate.” Equally good and bad is what Connolly calls “escapism,” the tendency of writers to daydream and romanticize the world into something better than it is. “We are all destroyed by the first escapist, Eve, and saved by the second who built an ark.” Sex is best avoided as an act, but undeniably important to write about. Success spoils you, but failure is worse.

Connolly exhibits the same impulse toward paradoxical aphorism in the book’s more descriptive opening discussion of various modernist styles. In America, Connolly is perhaps best known for his indictment of unrepentant “mandarinism,” and an early use of “Ivory Tower” to signify the social isolation of “high” modernist writers such as Proust, some of Joyce, and Virginia Woolf. Contemporary readers hear this phrase as pejorative, but, for Connolly, the Ivory Tower’s distance from mass tastes could be beneficial. He’s no less (or more) satisfied with the popular style of Hemingway that was then starting to dominate. He offers a clever collage of Hemingway, Orwell, and Christopher Isherwood to prove the creeping flattening of “middlebrow” style. Then he defends Henry James against H.G. Wells, and worries that Orwell, his schoolmate and champion against bullies, might become indistinguishable from other “mass writers”: “the talkie journalist, the advertising, lecturing, popular novelist.”

All of this “both, and” and “not one, and not wholly the other” rhetoric can start to seem like licensed sophistry, or a caricature of the consciousness and the “conscience” of a critic. Had “Enemies” consisted only of the sections on modernist style and the attempts to advise young writers of the 1930s, this latest reprint would not have been merited. Fortunately for him and for us, Connolly wanted to show that he came by his permanent dissatisfaction honestly. And so he puts aside the fictional authority of the critic and “disrobes in the vestry,” as he puts it, as though he were, in fact, the priest of a discredited religion. He then turns the book’s last section into an exquisite memoir of British school life and education between the world wars.

His portrait of that “weird and privileged and threatening and vanished society” could stand alone, but Connolly was adamant that his ambivalent recollections were a necessary supplement to his critical musings, that they emerged, organically, out of the criticism that preceded them — just as his criticism emerged from the personality that begins the memoir with yet one more self-annihilating sentence, “I have always disliked myself at any given moment, the total of such moments is my life.”

Those moments mainly consist of someone halfheartedly trying to fit in, first with an English public school system with which he was never comfortable. We feel the terrible unfairness of being educated to love one’s fellow boys, to die for them heroically, like Achilles and Patroclus, and then being told that homosexuality is a sin. If that wasn’t enough to turn one into a lover of paradoxes, there are also his wrestlings with the popular and populist trends in literature and politics, which he might have been expected to embrace but never could, entirely. Contrarian at the core, Connolly does seem to like himself very much, especially when he dislikes himself. Although he calls himself a failed writer and probably considered himself one, he makes this sense of failure seem something of a success.

It was only by setting his opposing tastes and tendencies against each other, in fact, that Connolly could get anywhere, and after so many unstable paradoxes, it’s tempting to reinterpret the title’s ambiguous genitive and make it into “Promising Enemies.” Writers will only survive and last if they pick the right ones. The choice of enemy, as much if not more than style or plot, is what ensures a book’s hope of “outliving a dog, or a car, of surviving the lease of a house or the life of a bottle of champagne.”

The persistence of Connolly’s enemies approves his choice of them, although their order of importance has changed and new ones have arisen. Our new information technologies appear to threaten the end of literature, or just the dream of the enduring printed word, something neither the Nazis nor Stalin could bring about. And professionalization doesn’t help either. As MFA programs turn more and more writers each year out on the market, who has time to untangle the paradoxes and pleasing complexity of any one of them?

Today, Connolly’s book would likely not even be published. The memoir might see the light, but pitched primarily as an account of veiled homosexuality at Eton. The essays in criticism would be discarded entirely, or retitled something like “How Fiction Works.” Now that every book has a category and a prefabricated place set aside for it in the bookstore, experience and advice, memoir, “career guidance,” and literary criticism are rarely yoked together, especially when they complicate each other.

But even a lease on a house lasts less time now than it used to and we drink our Champagne in great gulps whenever the power goes out. Still, what was true in the summer of 1938 remains true in the summer of 2008, “we must try to live and that for many of us means we must try to write, and very difficult it is.”

Mr. Roth is a founding editor of n+1. He is currently at work on a memoir about growing up as an intellectual on the Upper West Side.