NO excuses. Paul Theroux candidly acknowledges that in the 1970s he was prompted to compose travel books for the money.Were the writing of fiction more remunerative, legions of readers might not have train-trekked with Theroux through Turkey, India, China, and South America. To applaud the pernicious, longstanding financial inversion of nonfiction writing over fiction would be mean and misdirected. Perhaps, though, the publication of excerpts from six of Theroux's popular travel books is a moment in which to consider how powerful and indirect are the ways of inspiration. It would have taken compelling circumstances to convince Theroux - then an established, if financially embarrassed, author of fiction - to take up his pen as a travel writer. He harbored strong complaints about the conventions that have bedraggled the genre throughout this century. In Theroux's view, much of what passed for travel writing presumed that tourists cannot or will not deal with tough truths and unpleasant appearances. To him, travel books typically seemed to be "self-indulgent, unfunny, and rather selective." Moreover, with the development of mass tourism in the 1960s and 1970s, the goal of travel itself had contracted: "Everyone set off to see the same things," Theroux observes. Travel was no longer an experience - good or bad. It was a product. Both mass tourism and the travel writing it encourages easily survived Theroux's disparagement of them. Nonetheless, in the late 1970s there emerged a competing travel ethic that stressed encountering people from other cultures. Each in their own way, writers like Theroux, Calvin Trillin, Jan Morris, and Peter Matthiessen have helped to bring that change about. Intriguingly, Theroux suggests another cause for what has become known as cultural travel. He asserts that increased television viewing in the postwar decades provided sights to sightseers. (A similar societal effect was produced by the introduction of travel photographs in the 19th century.) Television - and photography - handily supplied consumers with the history and the look of faraway places. What these media could not do half so well was provide the pulse and perils of actual journeying. "The journey," Theroux writes, "not the arrival, matters." Leaving London in September 1973, on the trip that would form the crux of his first book, "The Great Railway Bazaar," Theroux could hardly be said to have been an enthusiastic traveler. By his own admission, he was loath to leave his family. His cheerless attitude was underscored by his writer friends, who belittled the idea of travel writing. Eventually his anxieties coalesced in such a way that he came to view the trip fatalistically. To assuage these tensions, Theroux distracted himself by making extensive notes on the minutiae of the trip, rather than the sights seen. Thus his well-regarded signature style was born out of self-therapy. With such a pronounced emphasis on the trip itself, and so little concern with arrival, it may seem that for all his perambulations, Theroux actually goes nowhere. In fact, he lingers in what for many of us would be inconsequential travel intervals. On a train in central Turkey, his conversations with a cluster of hippies on their way to India and with a Turkish entrepreneur become the basis of chapters on cultural disaffection. In Shaoshan, China, a visit to Mao Zedong's birthplace, neglected to the point of being a mockery of what it had been before Mao's fall from grace, occasions a fruitless search for a copy of the "Little Red Book," or any book by Mao. Like any tourist, Theroux goes to the Great Wall. But unlike most, he irreverently likens its swarm of tourists to "fleas on a dead snake." The difference between tourist writing and travel writing is evident in observations like these. Travel writing is stridently personal. Theroux is not about to modify his introspective discourses to suit the pieties and prettiness of guidebooks. When contemplating a remote Irish seashore, for instance, he cannot help but observe that the "coast ... so enchanting for the man with the camera, is murder for the fisherman." Indeed, there are times when readers accompanying Theroux will grow squeamish. Though he is not interested in partaking, he readily accepts a Madras taxi driver's intriguing proposition to take him to an English prostitute. When she cannot be found, Theroux becomes a somewhat hapless tourist surveying a wretched netherworld. In China, his curiosity again bests his repulsion, and he sits down to a clandestine banquet composed of endangered species. Often, reading Theroux is better than being there. "Travel," Theroux writes, has "to do with movement and truth, with trying everything, offering yourself to experience and then reporting it." For him, the journey is an "experiment with space." There are, of course, opposing and equally valid reasons to travel. Still, this compendium unequivocally offers insight into the mind of a foremost American fiction writer who became an accidental tourist.