BOOK REVIEW : Glimpse Into Mind of a Wayfarer : SIGNPOSTS IN A STRANGE LAND; <i> Walker Percy, Edited by Patrick Samway</i> ; Farrar, Straus & Giroux, $25, 428 pages

Sin, semiotics and sucking the heads off crawfish were among the lifelong preoccupations of Walker Percy, as we discover in “Signposts in a Strange Land,” a fat and satisfying anthology of the late novelist’s essays, public addresses, letters, interviews and other literary ephemera.

Percy secured his reputation as an American writer of enduring importance with half a dozen novels (ranging from “The Moviegoer” to “The Thanatos Syndrome”) that remain accessible and entertaining despite their solid philosophical and theological footings. The same interplay between light and dark, hilarity and gloom, can be observed in the 40-odd works of nonfiction collected here.

Percy was capable of dressing himself up as an Angst -ridden existential philosopher and, at the same time, a good ol’ boy from the Big Easy. Thus, for example, even a half-satirical essay on the pleasures and perils of bourbon-drinking turns into a celebration of bourbon as a specific remedy for “the anomie of the late twentieth century.”

“In Kierkegaardian terms,” Percy writes, tongue only slightly in cheek, “the use of Bourbon to such an end is a kind of anesthetized religious mode of existence, whereas connoisseurship, the discriminating but single-minded stimulation of sensory end organs, is the aesthetic of damnation.”

Walker Percy was Alabama-born, orphaned at 16, and briefly practiced medicine before inventing himself as a writer after a bout of tuberculosis put an end to his medical career. A lifelong student (and practitioner) of existential philosophy, and a late convert to Catholicism, his life’s work can be read as a restless contemplation of the friction between science and literature as tools of human redemption.

“Science teaches nothing about living a life” is how Percy sums up the spiritual crisis that drove him from practicing medicine into writing novels. “My question . . . was this: If there is . . . a gap in the scientific view of the world . . . and if the scientist cannot address himself to this reality, who can?” Percy mused out loud during a 1985 address titled “Diagnosing the Modern Malaise.” “My discovery, of course, was that the novelist can.”

Patrick Samway, editor of “Signposts,” presents his selection of Percy’s nonfiction under thematic headings that summarize Percy’s lifelong concerns: “Life in the South,” “Science, Language and Literature,” and “Morality and Religion.” And he allows Percy to sum up in a couple of remarkably revealing profiles, including a “self-interview” that Percy conducted with himself.

“How would you describe the place of the writer and artist in American life?”

“Strange.”

“Signposts” reveals Percy as the activist and the agitator, not just the ivory-tower intellectual, especially on the subject of abortion. He likens abortion to genocide and specifically invokes the moral example of the Nazis.

“It should not be surprising that present-day liberals favor abortion, just as the Nazis did years ago,” he proclaimed shortly before his death in 1990. “The only difference is that Nazis favored it for theoretical reasons (eugenics, racial purity), while present-day liberals favor it for consumer needs (unwanted, inconvenient).”

The work assembled in “Signposts” shows Percy in all of his moral and intellectual grandeur. Indeed, it appears that Percy was more likely to show off his considerable erudition in his essays and public addresses than in his fiction.

What shines through, however, is Percy’s fundamental decency, his compassion for the human predicament, and his abundant love for humanity, a love that expresses itself not as a generalized evangelical fervor but in a concrete appreciation for the individual, no matter how anguished or benighted, slouching toward Bethlehem.

“Percy believed profoundly in the simple ‘holiness of the ordinary’ in all its facets,” Samway reminds us. “The protagonists in his novels, everyday wayfarers whose lives are mysterious, dramatically reflect this.”

“Signposts” offers us a glimpse of what went on in the mind of one wayfarer in a life that amounted to an unrelenting quest. And, for the reader of Percy’s fiction, above all, “Signposts” is the subtext of Percy’s novels spoken out loud, an illuminating gloss on the body of work by which Percy earned his reputation in the first place.

Next: Richard Eder reviews “Bonneville Blue” by Joan Chase (Farrar Straus & Giroux) .