Duchess Regent of Milan, about 1475, suggesting a method of education suitable for her young son; and _Jacopo Sadoleto_ (1477-1547), humanist and churchman, friend of Luther, Melanchthon, Erasmus, and Sturm, and author of a book (1530) on education which indicates a return to the old Athenian ideal and type. [Illustration: FIG. 5.—Hieronymus Mercurialis: Title page of first edition of his _De arte gymnastica_.] Two other Italian writers are worthy of more extended notice. _Girolamo Cardano_ (1501-1576) had studied at Pavia and Padua, and traveled in France, England, Scotland, the Netherlands, and Germany. He obtained his doctorate in medicine and practised that profession, devoting much of his time, however, to researches which bore fruit in a long series of scientific and philosophical works. In his interesting autobiography he tells of his own early practice in running and jumping, riding, fencing, and swimming, and elsewhere describes at length a great variety of ancient and modern feats of strength and skill. His work on the care of health (_De sanitate tuenda, libri iv_), of which several editions appeared, contains an independent, systematic, and scientific treatment of the hygiene of bodily exercise, discussing its value and effects in general, the physiological classification of exercises into violent or light, rapid or slow, continuous or interrupted, etc., and the nature and usefulness of numerous special forms, which belong not only to past ages but also to contemporary life and customs. [Illustration: FIG. 6.—Hieronymus Mercurialis: Title page of second edition of his _De arte gymnastica_.]