What of scientific method occurred to Lord Bacon appealed even more to the intellectual genius of the Frenchman Descartes (1596-1660). A curious combination of sincere practicing Catholic and of original daring rationalist was this man, traveling all about Europe, serving as a soldier in the Netherlands, in Bavaria, in Hungary, living in Holland, dying in Sweden, with a mind as restless as his body. Now interested in mathematics, now in philosophy, presently absorbed in physics or in the proof of man's existence, throughout his whole career he held fast to the faith that science depends not upon the authority of books but upon the observation of facts. "Here are my books," he told a visitor, as he pointed to a basket of rabbits that he was about to dissect. The _Discourse on Method_ (1637) and the _Principles of Philosophy_ (1644), taken in conjunction with Bacon's work, ushered in a new scientific era, to some later phases of which we shall have occasion to refer in subsequent chapters. ADDITIONAL READING THE RENAISSANCE. GENERAL. _Cambridge Modern History_, Vol. I (1902), ch. xvi, xvii; _Histoire générale_, Vol. IV, ch. vii, viii, Vol. V, ch. x, xi; E. M. Hulme, _Renaissance and Reformation_, 2d ed. (1915), ch. v-vii, xix, xxix, xxx. More detailed accounts: Jakob Burckhardt, _The Civilization of the Period of the Renaissance in Italy_, trans. by S. G. C. Middlemore, 2 vols. (1878), 1 vol. ed. (1898), scholarly and profound; J. A. Symonds, _Renaissance in Italy_, 5 parts in 7 vols. (1897-1898), interesting and suggestive but less reliable than Burckhardt; Ludwig Geiger, _Renaissance und Humanismus in Italien und Deutschland_ (1882), in the great Oncken Series; F. X. Kraus, _Geschichte der christlichen Kunst_, 2 vols. in 4 (1896-1908), a monumental work of great interest and importance, by a German Catholic.