The shift from an exclusively text-based approach to the study of nature founded on the study of a limited number of authors, to a new one based on an enlarged encyclopedia and, above all, direct observation, reached its full expression at the time of Galileo Galilei; but it was already perceptible in the writings of Lorenzo Valla (circa 1406–1457)—who appealed to common sense against the absurdity of some of the Aristotelian tenets—and in those of Leonardo da Vinci, who invoked a virtuous interaction between science and practice. When Tommaso Campanella (1568–1639) stated that he learned more from the anatomy of an ant or an herb than from any book ever written, he was simply expressing in a beautiful and poetic form a shared methodological creed.