THEODORE DREISER An American Journey, 1908-1945 By Richard Lingeman Putnam. 544 pp. $39.95

BY THE FALL of 1911 Theodore Dreiser had published two novels that we now honor as American classics, Sister Carrie and Jennie Gerhardt, but that in their time were generally misunderstood and/or reviled for their indifference to the taboos of the Victorian age. He had in mind another novel that would explore "the American man of affairs and millionaire as he has never yet been interpreted," but he needed to do research in Europe and was, as usual, short of funds.

Then a British publisher came to his rescue, arranging a grand tour that took the lumbering Midwesterner through most of the continent's notable landmarks. Dreiser left in November for what proved in many ways a useful trip -- his aversion to England softened upon direct exposure to the country, and he was stirred to be in the land of his German ancestors -- but its most instructive lesson was unanticipated. As Richard Lingeman puts it in this, the second and last volume of his massive biography:

"Europe was the past, America the new Colossus of trade and industry, with its conquering capitalists and financiers . . . In Europe he had clearly recognized that he was irrevocably an American writer. His subject was the energy and change of its cities, where achieving, not living, was the watchword, where life was attuned to a jagged ragtime beat."

He was neither the first nor the last American who had to cross the Atlantic in order to acquire a full understanding of his own identity and his literary subject matter, but few learned the lesson more fully than he. With the immense concentration of which he was capable, he turned himself to the story of Frank Cowperwood, whom he modeled closely upon a now-forgotten mogul named Charles T. Yerkes. In only half a year the first volume, The Financier, was published; it was followed a year later by the second Cowperwood novel, The Titan; then, in 1925, after a long period of difficulty, came An American Tragedy, the book that secured both his reputation and his financial security.

In a quarter-century, then, beginning with Sister Carrie in 1900, Dreiser wrote five novels that are, as Lingeman says, indisputably "great works," but that are more: They are particularly, peculiarly and indelibly American. They attempt to embrace the whole spectrum of American life, from the most obscenely rich to the most desperately poor, and they address a conflict that is every bit as much American as it is Dreiserian: "On the one hand he admired and envied the famous rogue-builders of American capitalism, reflecting his own boyhood ambitions . . . and his strong lust for power. On the other, his acute sense of social justice condemned them as exploiters of the common people."

This is not the only theme that courses through these dense, passionate, populous novels, but it is the dominant one. Conflict takes innumerable forms in Dreiser's work, as it did in his life, but it is never absent. He wrote at a time when belief in the eventual triumph of the melting pot was still widespread, but he understood, both viscerally and intellectually, that strife -- social, economic, political, ethnic and racial -- is for better and worse the real American dynamic, and he explored it ceaselessly in the best of his fiction.

Of that fiction, four of his five masterworks were written during the years covered in this second volume; the first, Theodore Dreiser: At the Gates of the City, 1871-1907, is concerned with his long apprenticeship, his labors as a magazine editor, and the public outcry with which Sister Carrie was greeted. Yet if the years from 1908 to 1945 were productive, they were also frustrating, difficult and -- this perhaps above all else -- tempestuous. Dreiser wrote four magnificent novels, but he also wrote two others -- The Genius and The Bulwark -- that fell far short of his high expectations, and at his death he left an incomplete manuscript of The Stoic, the last of the Cowperwood novels, that in its posthumously published form fell far short of its two companions.

In large measure Dreiser seems to have failed in these enterprises because he became bogged down in philosophical speculations; his instincts were visceral and his methods were reportorial, and when he attempted to turn intellectual he invariably managed to be at once overwrought and half-baked. But his literary pursuits cannot have been helped by his sexual adventures, which were so busy that "at times it would have taken a Mack Sennett to direct the complicated exits and entrances" of the many women who flocked to the various studios and boudoirs in which he held court.

Dreiser's amatory successes must certainly be counted among the great mysteries of the age, or else as testimony to the unfathomable mysteries of the human psyche. He was awkward, crude and apparently charmless, yet women seem to have been unable to resist the clumsy advances that he pressed without thought of rebuff. Marriage was no encumbrance; his days were spent in a relentless quest for the "ideal woman, who would forever be younger, prettier, richer, more loving, more brilliant, more sacrificing than the woman he was with." His obsession was so powerful that "there was some feeling in {his} family that he was abnormal, even talk that he should be sterilized."

It's a good thing he wasn't; what Lingeman calls "the explosive power of love" is central to his fiction, most obviously to An American Tragedy. Without it he doubtless would have had more time for his writing table, but without it he also would have been deprived of the passion that permeates his work, that makes it so distinctively his own.

Lingeman is, as he should be, an advocate of that work; he has read it closely and understands its salient characteristics, among them its realism, its sympathy for "a wide range of characters, including those with whom he disagreed," and its acute understanding of "the psychological, economic and social structure that undergirds class and manners." On other matters, though, he is less successful. Confronted with a massive amount of documentary evidence, he has been unable to resist its temptations; his accounts of Dreiser's squabbles with publishers and censors and other malefactors are interminably detailed, and even his descriptions of Dreiser's dalliances and conquests eventually become so repetitious as to lose most if not all interest.

The result is a book of excessive length and daunting price; at $39.95, it is likely to find its way into few shelves except those of the libraries. This, its shortcomings to the contrary notwithstanding, is a pity. Whatever its superfluities, Lingeman's Dreiser is a careful, discerning book that pays all due respect to one of the few American novelists who, without embarrassment or exaggeration, can be called great. But realism is out of fashion among the literati these days, and Dreiser's stock is not high; if Lingeman helps raise it, he will have performed an invaluable service.