Nonfiction briefly noted. . .; Vol. 1 of new Liszt biography; Franz Liszt: The Virtuoso Years, 1811-1847, by Alan Walker. New York: Alfred A. Knopf. 481 pp. $25.

Unlike many musical idols whose talent is surpassed only by their ego, Liszt found his ideal in self-abnegation. Even as a teen-ager he pondered these words from Thomas a Kempis: ''Learn to make thyself meek, thou earth and clay, and to bow thyself under the feet of all.'' Small wonder in later years he took vows as a monk.

In the first of three planned volumes, Alan Walker traces Liszt's career from his beginnings as a child prodigy in Hungary until his retirement from paid concerts at age 35 - at the peak of success. With a decade of research behind him, Walker is in a position to settle long-standing controversies. He stresses that Liszt was not of aristocratic origins; he was given a ''kiss of consecration'' by Beethoven; he was not cynically exploited by his father; he was the author of an opera at age 13; he did not leave his mistress Marie d'Agoult for ignoble reasons.

Walker is a professor of music, and it shows. Although generally quite readable, his book is intended as a scholarly study. For example, Liszt's breakthroughs in keyboard technique are discussed in terms that will be understood only by fellow musicians. Still, Liszt's basic contributions as ''the first modern pianist'' come across clearly even to the uninitiated. So does his character as a man.