It is not the fault of Speed Lamkin '48 that the decay of Southern aristocracy and its struggle against industrialism are old stuff to most of us by now. One cannot expect a novelist in his early twenties to present many fresh insights into situations that have been so completely explored by more seasoned writers.

But although Lamkin's tale of an aristocratic family's decline in a back water Louisiana town seems to have been told before, the author's thorough understanding of his subject matter prevents his first novel from becoming merely an echo, hollow as the life of his virginal, bachelor story-teller, Henry Nelson.

"Tiger in the Garden" follows the Richardson children, Caroline, Percy, and Byron, from their genteel childhood before World War I, through Caroline's scandalous elopement with Joe Conway, a man of no social standing with whom all women want to sleep: through Percy's drunkenness, debauchery, homosexuality, and early death. Conway, at first scorned by his in-laws, makes a fortune when oil is discovered in the old cotton fields, and periodically escapes the sterile Richardsons by running off to New Orleans with a lady of fashion and culture.

Eventually, Caroline avenges herself on Conway, crushing his spirit with forgiveness, and, aided by the crash of '29, manages to ruin both their lives while doggedly attempting to prepare her nephew for the grand noble role she and her brothers were never quite able to fill.

Oddly, for a young novelist, Lamkin has put his story in the words of a middle-aged man. Henry has grown up with the Richardsons, as one of their "poor cousins." All his life he has lived in the double shadow of the Richardson grandeur and his own mother. In a languid, casual prose that reflects his own insipidity, Henry tells his cousins' story, while he himself is changing from an absolute disciple of the noble Richardson myth to a disillusioned old bank clerk who decries its "false majesty."

But we never understand exactly what it was that disenchanted Henry, and this uncertainty embraces the whole novel. The author can see the barreness of his subjects' lives and dreams, and yet his sympathy for them forces him to admire their persistence in the face of certain defeat.

Technically, the novel is weak. The loose, rambling prose does out take hold of the reader until the genuinely rich plot begins to move by itself. Lamkin falls to take advantage of the dramatic situations he has devised, and much too often he uses the hack writer's crutch of divulging information about one character through the lips of another. It is true that this indirectness of style produces a wispy, unrealistic effect that is appropriate to the subject matter, but at times it becomes apparent that Lamkin does not yet know how to explain a character's motives effectively.

Speed Lamkin still has much to learn about writing. But at 22 he has already mastered one of the writer's fundamental implements: the ability to understand motives and desires of many kinds of people.