William H. Gass has been America's best living essayist for an obscenely long time. From the 1960s, when critics loved theory more than reading, to our present moment, when the flicker and fidget of computers makes deep immersion in a book rarer, Gass' voice has been a clarifying balm. To read him is to remember there are no ideas without language. Its muchness becomes music in his hands. He is a maestro, and, nearing 90, has lost none of his word-drunk passion.

If anything, Gass is reaching a kind of crescendo, as "Life Sentences: Literary Judgments and Accounts," his fifth book of essays, beautifully reveals. At a glance it resembles a collection of literary essays. There are pieces on Nietzsche and James, and Katherine Anne Porter. He accepts an award or two. But open one of these essays and you will quickly realize this is a book about how language gives meaning and shape to a chaotic world.

He does not cudgel wisdom from texts, but rather demolishes the barrier we so often place between books and consciousness.

He begins, appropriately, with a few autobiographical notes -- stories that recall his own verbal consciousness emerging. "Slices of Life in a Library" portrays the young critic outfoxing nighttime guards to camp out until morning in the Cornell University library. "Spit in a Mitt" conjures his father's years in minor league baseball through the stories the old man told and retold, probably, as Gass writes, "because those good sweet years were now so far away, as are the small parks, the ardent crowds, and the grass which would shine its green shade on a player's palm."

On the page, Gass' presence is wise, avuncular and sympathetic to human weakness -- a pose that makes him a great reader of writers' lives. The book's gem is a long piece on Nietzsche and illness, which reminds us that the German philosopher was under constant and contradictory medical attention. "Leeches were encouraged to feed on the lobes of his ears. He was often under his mother's care, and he was frequently so sick he had to summon his sister to his side, though she was not at the time nearby."

Time and again in "Life Sentences," Gass bears witness to the spooky miracle of finding a writer's consciousness alive and present on the page. "Life Sentences," with its dour, slightly terminal title, is then a book of reanimations. In an introduction to John Gardner's "Nickel Mountain," Gass describes how "characters rise from the page as John wished them to, and stride into their story." Like all the best critics, Gass almost makes us forget that he is standing behind them, giving them a gentle shove.

John Freeman is the editor of Granta and the author of "The Tyranny of E-mail."