Astonishing though the fact may seem, it is now fully a half-century since a young writer from Georgia named Erskine Caldwell first outraged the residents of his native region and startled readers just about everywhere else. The occasion has this month been celebrated with the publication by Signet of paperback reissues, each prominently identified as a "Special 50th Anniversary Edition," of Caldwell's two most popular and controversial novels, "Tobacco Road" and "God's Little Acre." And to round out the festivities, Caldwell will celebrate his 80th birthday later this week.

As has often been the practice with paperback editions of Caldwell's work, these new ones proclaim the extraordinary success the books have enjoyed: "Over 3.5 million copies sold!" announces the jacket of "Tobacco Road," while "God's Little Acre" outstrips it with "Over 8 million copies sold!" By the standards of such as Jacqueline Susann, Harold Robbins and Mario Puzo, these figures may be nothing to get excited about, but for a writer who might otherwise be placed in the catchall category of "minor regional novelist," they are entirely spectacular.

It has never been difficult, though, to explain Caldwell's large following. Although he writes almost exclusively about impoverished Southern country people, he does so with a humor and salacity that appeal to more sophisticated audiences -- and he balances his bawdiness with a rather sentimental moralism that lends the novels a certain respectability. Further, large numbers of readers have been lured to his books by adaptations of them, the most notable being the Broadway version of "Tobacco Road"; it ran for a total of 3,182 performances, exceeded only by "Grease," "Fiddler on the Roof" and "Life With Father."

It's unlikely that many readers born after World War II can fully appreciate the shock waves that were caused by the initial appearance of these two books: "Tobacco Road" in 1932 and "God's Little Acre" in 1933. Prevailing moral strictures may have been relaxed somewhat by then as a consequence of the middle-class excesses of the 1920s, but they were relaxed only by comparison with what went before; explicit description of sexual behavior was almost unheard-of in respectable publications, and the use of euphemisms in place of profane language was commonplace. Caldwell's people didn't talk dirty, but they acted dirty; the nation, to put it mildly, was taken aback.

The shock value of "Tobacco Road" lay largely in its depiction of a South with which the rest of the nation was scarcely acquainted, the South of the poor white trash; there is relatively little sex in the novel, and it is described quite obliquely. But "God's Little Acre" was a clear slap at the moral standards of the day. Its two most famous scenes -- Will Thompson's seductions of his sisters-in-law, Darling Jill and Griselda -- brought a new eroticism into polite bookstores and made Caldwell a major target for the bluestockings. Not until the 1960s, when all restrictions on description of sexual activity collapsed, did "God's Little Acre" come to be viewed as tame; and its power to titillate is, even now, greater than that of most novels that treat sex with clinical, monotonous, joyless detail.

Unfortunately, though, a rereading of "God's Little Acre" on the occasion of its golden anniversary does not encourage me in the belief that much of a future is left to it. The chief reason to read it now is as a period piece: a reminder of how easily middle-class America could be shocked and outraged a half-century ago. As a work of fiction, much less literature, it has less to recommend it. Its tone alternates so unpredictably between the comic and the melodramatic that the reader feels constantly out of step; its sermonizing against the evils of "those rich sons-of-bitches who run the mill" is, if deeply felt, lame and predictable; much of the dialogue is stilted. It is tempting, though perhaps the temptation should be resisted, to conclude that Caldwell was more interested in creating a sensation than a serious work of fiction when he wrote "God's Little Acre."

"Tobacco Road," by contrast, holds up surprisingly well. From first page to last Caldwell sustains a jauntily comic, mocking tone that is not altered even by the incineration of Jeeter Lester and his wife Ada. In all of American literature there is no more shiftless clan than the Lesters, and Caldwell portrays their collective inertia with a wry amusement that is most appealing, as is his intimate knowledge of hill-country folkways. Furthermore, Caldwell has the breadth of vision to see that Jeeter Lester is the victim not merely of his own laziness but also of limited opportunities. He portrays Jeeter not as a redneck caricature but as a fellow of a certain dignity:

"There was an inherited love of the land in Jeeter that all his disastrous experiences with farming had failed to take away. He had lived his whole life there on a small remnant of the Lester plantation, and while he realized it was not his legally, he felt that he would die if he had to move away from it. He would not even consider going elsewhere to live, even though he were offered a chance to work another man's farm on shares. Even to move to Augusta and work in the cotton mills would be impossible for him. The restless movement of the other tenant farmers to the mills had never had any effect on Jeeter. Working in cotton mills might be all right for some people, he said, but as for him, he would rather die of starvation than leave the land. . . . "

This comprehension of the humanity beneath the rough and raffish exterior of the unlettered rustic is Caldwell's most attractive and durable characteristic. It is all well and good for him to rail against the rich and powerful and to embrace the cause of the common man, but what really matters is his understanding of the workings of that man's mind and his sympathy for the fix in which through no fault of his own he finds himself. It is doubtless too much to expect that he will still be widely read after another half-century has passed, but the successes of the past five decades were honorably earned.