In her essay "On Keeping a Notebook," Joan Didion described how the "impulse to write things down is a peculiarly compulsive one, inexplicable to those who do not share it, useful only accidentally, only secondarily, in the way that any compulsion tries to justify itself."

In the case of SOUTH AND WEST: From a Notebook, two uneasily paired slices of 1970s Americana extracted from Didion's notebooks, she offers much more than that diffident description would suggest. As Nathaniel Rich describes it in the book's foreword, it's a revealing "glimpse inside the factory walls" of her lifelong literary project and provides further evidence to support Didion's claim for recognition as one of the great practitioners of modern narrative nonfiction.

SOUTH AND WEST admittedly is slight. The pieces it comprises --- the account of a trip Didion took with her husband, John Gregory Dunne, through Louisiana, Mississippi and Alabama, and some fragmentary reflections she recorded in anticipation of an article for Rolling Stone on the Patty Hearst trial in 1976 --- add up to barely more than 100 pages. Despite that brevity, together they're finely etched miniatures that highlight Didion's cultural and political preoccupations, her powers of observation and her inimitable style.

When the 35-year-old Didion took off with Dunne in a rental car from the New Orleans airport in June 1970, she'd already made her literary presence felt with the nonfiction collection SLOUCHING TOWARDS BETHLEHEM and the novel PLAY IT AS IT LAYS. Of this trip, she writes, "The idea was to start in New Orleans and from there we had no plan," and their pre-GPS-era journey seems to have remained true to its formless origin.

"The pieces it comprises...add up to barely more than 100 pages. Despite that brevity, together they're finely etched miniatures that highlight Didion's cultural and political preoccupations, her powers of observation and her inimitable style."

The account is divided into sections with spare headings like "Pass Christian to Gulfport" or "Swimming at the Howard Johnson's in Meridian." Didion's reporting ranges from an uneasy visit to the Reptile House (featuring a chillingly named Snake Pit) to a lengthy conversation with Stan Torgerson, the white owner of the black radio station in Meridian, Mississippi. What's unusual about "Notes on the South" is that, although Didion says she "never wrote the piece," she may have contemplated when her journey began, for its occasional rough edges the work feels entirely complete and satisfying.

Apart from the rich eccentricity of its local color, the region Didion describes six years after the passage of the Civil Rights Act of 1964, its "solidarity engendered by outside disapproval," is one in a "time warp: the Civil War was yesterday, but 1960 is spoken of as if it were about 300 years ago." That becomes clear in the course of her conversation with Torgerson, who "cannot think of any place where the black is denied entrance, with the possible exception of private clubs," and who offers to "pit our slum area any day against the slum areas where the Cubans and Puerto Ricans live in Miami, Florida, and Miami'll lose."

A languid Sunday afternoon conversation with Clarksdale, Mississippi farmer Marshall Boudin dwells on what he describes as "the last of the feudal system." For all his self-professed moderation, Boudin's commentary only reinforces the picture of a region suspended in time, more GONE WITH THE WIND than the New South of cosmopolitan Atlanta.

But the pleasure of reading Joan Didion lies as much in style as it does in substance. Her vision is so acute and her word portraits so vivid that it's almost possible to see the encircling kudzu and feel the humidity dripping from the Spanish moss, as when she describes the "somnolence so dense it seemed to inhibit breathing" that hung over Hattiesburg, Mississippi one mid-afternoon.

That same skill extends to a snapshot of New Orleans in June, where "the air is heavy with sex and death, not violent death but death by decay, overripeness, rotting, death by drowning, suffocation, fever of unknown etiology." And it includes a description of her own emotional state on the journey:

"It occurred to me almost constantly in the South that had I lived there I would have been an eccentric and full of anger, and I wondered what form the anger would have taken. Would I have taken up causes, or would I have simply knifed somebody?"

The 13 pages of Didion's "California Notes," which contain material that found its way into her 2003 memoir, WHERE I WAS FROM, are much more sketchy. Though they were assembled in aid of the projected Patty Hearst piece, Didion quickly concedes that the entry is "not about Patricia Hearst. It is about me and the peculiar vacuum in which I grew up, a vacuum in which the Hearsts could be quite literally king of the hill."

Still, even these fragments are illuminated by the lightning flashes of Didion's impressionistic prose:

"The snow still falls in the Sierra. The Pacific still trembles in its bowl. The great tectonic plates strain against each other while we sleep and wake. Rattlers in the dry grass. Sharks beneath the Golden Gate."

"But our notebooks give us away," Didion wrote in "On Keeping a Notebook," "for however dutifully we record what we see around us, the common denominator of all we see is always, transparently, shamelessly, the implacable 'I.'" The "I" of Joan Didion's writing remains at the heart of these pieces --- small but generous gifts she now finally has allowed her readers to enjoy.