QUATrROCENTO medical writings have fascinated few modem historians of medicine. Despite Lynn Thorndike's masterful challenges to it,' George Sarton's view has generally prevailed with investigators, that for science the Italian Renaissance, while perhaps a period of preparation, was certainly a period of dissolution.2 Although in recent years historians have come to realize that Vesalius' achievement was built on a tradition of anatomical investigation that developed in the Italian universities during the fourteenth and fifteenth centuries,3 they have disregarded in large part the clinical writings of the academicians who-lectured on medical topics in the same institutions. Historians of embryology and generation in particular seem to have ignored the works of the physicians whose interests led them to consider these subjects during the period between the lives of Mondino and Leonardo da Vinci,' and in consequence, have overlooked a curious but significant account almost hidden in a medical encyclopaedia compiled by Giovanni Michele Savonarola. The purpose of this paper is to present Savonarola's description of an obstetrical rarity, to examine his explanation of it in light of the sources he believed to be authoritative, and to demonstrate how it and certain other obstetrical phenomena not only may be elucidated by modem findings, but may illuminate the medical thought of his age. Since the account is contained in Savonarola's Practica major,5 it seems appropriate to review briefly some of the facts known concerning the life and writings of that distinguished but ever genial student of human nature.6 Overshadowed by the dramatic and tempestuous events in the career of his grandson Girolamo, Michele Savonarola's medical works and accomplishments are generally neglected.7 He deserves better treatment. A physician and philosopher, he was an illustrious member of the intelligentsia of his time. His life, the many and diverse works that he composed, and the role that he played in the society of the Italian Renaissance place him among the most influential and enlightened personalities of Northern Italy during the middle of the fifteenth century. Born in Padua around 1385, Savonarola died at Ferrara, some time after 1461 and perhaps as late as 1468,8 having lived a life that was divided between the two cities. A student and later a professor at the University of Padua, he moved to Ferrara in his fifty-fifth year, and remained there as physician and councillor to the d'Este rulers until his death.