As an historian I have always been interested in the problem of defining historical periods and understanding the transitions between them.How, for example, did the Middle Ages, with its religious, world-denying culture, give way to the world-embracing, life-affirming culture known as the Renaissance?This was the perspective from which I began to study Savonarola, seemingly a representative of the first of these worlds who was embraced and exalted in the second.Gradually I arrived at a new understanding of Fra Girolamo and his reception. In so doing I had to discard the conventional labels that distort him and also to reject the practice of freezing history into such hard and fast designations as “Middle Ages” and “Renaissance.”I would also like to share two historical lessons I have learned: one, the inadequacy of historical labels such as “medieval” and “modern,” and the limitation of moral judgments—such as “saint,” “fanatic,” “charlatan,” and “demagogue”—in explaining the behavior and ideas of charismatic figures; two, the complex psychological, social, political and ideological reasons behind peoples’ belief in and rejection of their heroes and leaders.