THE LONE HERETIC by Margaret Thomas Rudd. 349 pages. University of Texas. $6.50.
There was never a man who thought better of himself than the philosopher Miguel de Unamuno. Even in Spain, his ego was a marvel. "Years after you have left my classroom," he told his students, "you will have forgotten what I may teach you, but you will never forget me." When the King of Spain presented him with a medal for his writings, Unamuno said only: "I deserved it." When his fellow philosopher Ortega y Gasset suggested that they collaborate on an educational scheme, Unamuno turned him down: "What...