The twentieth century's greatest American dissenter has written a study of the five men whose own dissents helped shape the western world -- Socrates, Galileo, Tom Paine, Wendell Phillips, and Gandhi. Conformity to custom, Mr. Thomas believes, is essential to the human community; it provides a base for judgment and security, Progress, however, depends on those who go beyond custom in search of the truth and thus cause us to reappraise our loyalties. Heresy, then, is the growing part of the social tree. Mr. Thomas has chosen men whose dissents were not born of rebellious natures, subjective...