Lyndon, An Oral Biography, by Merle Miller. New York: Ballantine Books. $9 .95.

Every aspect of Lyndon Johnson's personality and tumultuous career, from birth and youth through his 24 years in the Congress -- including his violently curtailed vice-presidency and ill-starred presidency -- are covered and re-covered in this comprehensive volume. The biography, made up of conversations with Johnson's friends and associates, come over like its subject, overwhelmingly. Inevitably the reader is left still guessing about an infinitely complex person, yet is compelled to read every single line of the 560 pages.