But Sadie Plant manages to make her subject compelling. In large part, this is because she is intelligently agnostic about almost everything relating to drugs: She avoids falling into the almost inevitable banality that attends either Timothy Leary-style cheerleading or know-nothing moralizing. The fact that she doesn't exactly deliver on her book's title also helps her. "Writing on Drugs" does provide highlights from the extensive literature on drugs, but it incessantly meanders away onto other subjects, from the way that certain drugs reflect the obsessions of their eras to the possibility that broom-sitting witches absorbed psychoactive drugs through their vaginal membranes to the hypocrisy and self-defeating nature of assorted wars on drugs.

This somewhat invertebrate, not to say dazed and confused, approach prevents Plant from getting caught in the epistemological quagmires that trap those given to making sweeping theoretical pronouncements about drugs. But it also gives "Writing on Drugs" a free associative, at times anarchic, feeling that sometimes recalls, it must be said, certain conversations carried out in the shadow of the spliff. (This may be an occupational hazard of immersing oneself in drug writing, a kind of literary contact high.) As with those conversations, this is only intermittently a good thing. One wishes that Plant had pursued some of her suggestive ideas and themes more exhaustively and with greater rigor. Fortunately, however, she's a smart and lively enough writer that most of the time, you don't mind her flitting.

The book opens with a brief, autobiographical prelude that recalls an opium-fueled reverie in Thailand. Aside from this bit of poetic semi-confession, Plant does not divulge the extent of her own drug use, although her descriptions of the effects of ecstasy seem unusually vivid. This reticence is understandable: As she tersely notes, "Drugs take all authority away." (Still, it would not seem amiss, in this exploration of the most subjective of literary genres, for the author to come clean about her own experiences and what they have meant to her.)

Plant begins her tour in the 19th century, in the golden age of drug writing, when writers like De Quincey, Coleridge and Baudelaire encountered opium. "There is something about opium, with all its varied properties and histories, that allows this drug to set the scene," she writes, quoting Jean Cocteau as saying "Of all drugs, opium is the drug." These artists' experiences with opium encapsulate the dichotomies attached to all drug use: The ecstatic visions and shattering insights of the drug experience vs. the enervation, depression and sense of flatness that can follow; the persistent sense that neither reality nor the self is fixed -- a radically relativistic doctrine that Nietzsche called perspectivism -- vs. the equally strong sense that beneath the shifting veils lies one reality; the literally self-preserving impulse toward caution and measure, what Rimbaud called "a rational derangement of the senses" vs. Artaud's Dionysian call for complete surrender to the unknown.

Cocaine, which followed opium, played an opposite social role, Plant argues, engaging people with the speeded-up world they had tried to escape by chasing the dragon. "If opiates had provided De Quincey's generation with a means of escaping the ravages of the mechanical age, coca and cocaine woke everyone up to an era humming with new distributions of power and new forms of mass communication," she writes. Some of the more entertaining passages of "Writing on Drugs" recall the grandiose health claims made by manufacturers and the medical establishment alike for cocaine, which was extolled as a supreme boon to health, vigor and happiness. Products like "Peruvian Wine of Coca" and "Vin Mariani" were said to fortify and refresh the body and brain. The architect who designed the Statue of Liberty raved that "Vin Mariani seems to brighten and increase all our faculties; it is very probable that had I taken it 20 years ago, the Statue of Liberty would have attained the height of several hundred meters." A high achievement indeed.

Maya Angelou reads from "The Heart of a Woman"