Spain's foremost writers: Cervantes -- keen satirical insight Cervantes, by Melveena McKendrick. Boston: Little, Brown & Co. $11.95.

If today's writers complain that literature is an unreliable livelihood, those of the 16th and 17th centuries had even greater cause. In an era of capricious patronage, enormous class distinctions, rampant illiteracy, and great physical dangers, a talented man could rarely afford to assert his creative genius. The luxury of self-expression would be even rarer in a man who was neither rich nor highborn, who spoke with a stutter, and, as a soldier, had lost the use of one hand.

That just such a man, Miguel de Cervantes Saavedra, became Spain's most celebrated author is testimony either to extraordinary good fortune or magnificent courage and will. Melveena McKendrick, author of "Cervantes," takes the latter view. Her biography shows that circumstance almost never aided Cervantes, except by providing him with the richness of knowledge and experience that informs his finest work.

According to McKendrick, if Cervantes had not suffered so greatly, he might never have developed the keen, satirical insight never left with just another writer of passably good poetry, drama, and pastoral romance, and the world would have had to wait for another writer to mold the modern novel.

McKendrick believes the experiences of an author offer an important key to his work and that a book is not just an organic entity that stands alone. At every turn, McKendrick shows that the misfortunes which deprived Cervantes was carrying letters from highranking Spanish officials recommending him for a captaincy, he was captured by Barbary pirates. Mistakenly thinking that he must be a person of great importance, they held him in Algiers as a slave for five years, awaiting a rediculously high ransom.

To reconstruct these years and other shadowy periods in the author's existence, McKendrick has analyzed every remnant of evidence. The resulting portrait is unremittingly admiring. According to her interpretation. Cervantes's life was spared after four escape attempts not only because of his supposed worth, but because of his great courage and character. She sees the later discrepancies in his accounts and receipts while a naval commissary and a government tax collector as the result of financial bungling and excessive "generosity" -- never embezzlement.

If he neglected his duties as a husband and father, she says, it was only because he believed in the principles of freedom for his wife and illegitimate daughter. And if other critics accuse him of amorality because he seems to support no specific philosophy, McKendrick believes that he merely took his faith for granted. Although McKendrick's view may be overly generous (no one can really verify it), she supports it well, usually by referring to official documents and the events of the time.

What makes her conclusions all the more believable is that she also stubbornly adheres to history in her interpretation of Cervantes's work. Although contemporary critics may see "Don Quixote" as the first great existentialist statement or as a celebration of the indomitable human spirit, McKendrick insists that we start with the text itself. Cervantes intended "Don Quixote," she says, as no more and no less than a wonderfully inspired parody of chivalric romance, commenting on the absurd obliviousness to reality that characterized both Spanish literature and politics at the time.

Cervantes's purpose, however, did not include the transformation of Western literature. His legacy of realism seems almost another irony in a life distinguished by unusual twists. If McKendrick's thesis is correct -- that "the realm of disillusion arguably inspires greater and more lasting literary artifacts than the idealism of hope" -- then Cervantes's years of soldiering and servitude were not wasted. This compelling biography, however, still leaves the reader wondering what he might have produced if those years had been given back to him.