He lived with a frantic and desperate intensity, and he died horribly and in character.

John Gardner, who was killed yesterday in a motorcycle accident near his home in Susquehanna County, Pa., had driven his talent as hard as any writer in American letters. He was 49, and had already written more than two dozen novels and plays, as well as numerous stories, poems, librettos, works of criticism and an epic poem. He had taught for nearly 30 years at nine universities, establishing a reputation for tireless generosity to students. He had founded and edited the literary magazine MSS. And he had become a bohemian legend in the literary world with his nonstop martinis, leather jerkins, shoulder-length shock of silver hair and the brutally powerful Harley-Davidsons he had been riding since his teens.

Yet his art was as scrupulous and earnest as his image was wild. Fiction should be "a vivid and continuous dream," he believed, and said in an interview last July that "in all my work, I'm trying to break down the distinction between reality and fiction, to make the world fiction, to get back to the real real world, where all the myths are true." His philosophical narratives often took the form of ethical dialectics enacted in mythic or magical settings, evoked in vibrantly keen physical description and enhanced by a profusion of metaphor.

His superbly haunting and poetic reconstruction of the Beowulf story, "Grendel," (1971) was cited by Time and Newsweek as one of the best novels of the year. The New York Times called him "a major contemporary writer," a distinction he confirmed with "The Sunlight Dialogues" (1972), an ambitious examination of the anarchic moral forces loose in the '60s. It became a best seller, followed by the brooding comedy "October Light" (1976), which won the National Book Critics Circle Award. In his landmark critical study, "On Moral Fiction" (1978), he said, "I agree with Tolstoy that the highest purpose of art is to make people good by choice." His demand that fiction provide "life-affirming, just and compassionate behavior" provoked a heated national debate about the state of the novel. When he died, his new novel, a philosophical, supernatural thriller, "Mickelsson's Ghosts," was still in the stores. And Gardner was at work on two more, hopeful of an esthetic breakthrough: "I've tried to tear everything that I've done apart," he said in that July interview, "and do something different."

But if he was pushing his genius relentlessly, he was pushing himself even harder. He drank heavily, chain-smoking pipes and cigarettes, many times carousing until dawn. Whether at the Bread Loaf Writer's Conference or at the State University of New York at Binghamton, where he headed the creative writing program, he worked and played at a fierce pitch that even his friends feared was self-destructive. Mickelsson, the boozy professor of his last novel, is "a man who's destroying his career," Gardner said this summer. "He wants to start over. And so on a sort of unconscious level he does everything in his power to wreck himself. It's mad . . . but it's sort of heroic." And autobiographical? "I am Mickelsson in a sense."

Within a space of two or three hours, Gardner could display a bewildering spectrum of moods. He would be a mesmerizingly charming raconteur, eager to lavish praise on fellow writers, swinging his fuming pipe in a flourish of barroom gregariousness. He would be by turns defensive -- "I'm absolutely loved in the Midwest and West" -- and humble about his own work: "I grew up and began to understand Bellow," he'd say, or "Yeah, I'm coming around to Updike. You know, I'm slow." Then at times his face would suddenly darken and his voice go bleak with woe, as if recalling -- after two failed marriages, thoughts of suicide, awesome debts owed for back taxes, surgery for colon cancer, and the terrible enmity of many writers he castigated in "On Moral Fiction" -- a life too surfeited with sorrow and the long legacy of guilt.

As a boy, he was driving a tractor on his parents' farm near Batavia, N.Y., when his younger brother was crushed under the machine. He would "watch it happen in his mind," Gardner wrote in a short story about the event, "with nearly undiminished intensity and clarity, all his life." He blamed himself for the death. "I was terrific at guilt, and I did everything in my power to get guiltier," including racing motorcycles as a teen-ager. "I'm still a motorcyle kid" at heart, he said, recalling how he used to run "flat out," how "when you get near the finish line, you'd just put your hands down on the bars like this" -- plopping on the table, elbows splayed -- "and then you'd stick your head under."

The same image occurred to him later. He had been "badly hurt" by the generally lukewarm or negative reviews of "Mickelsson's Ghosts." "These people in New York have decided that John Gardner is no good." Eyes dropping, the pipe masking his face, he said he was too depressed to write. But soon the mood began to lift. "You know, I think I'm a really great artist . . . It's the same thing as motorcycle racing. You believe in something and you push it and you just don't worry about what's going to happen."