In the midst of his great Historia animalium (History of Animals, 1551–8), the Swiss-German naturalist Conrad Gessner (1516–1565) offered the following reflection on the process of creating knowledge. “Reason and experience are the two pillars of scientific work,” he affirmed. “Reason comes to us from God; experience depends on the will of man. Science is born from the collaboration of the two.” Gessner’s experience gathering materials for a new history of nature in the mid-sixteenth century gave him direct insight into the problems of combining reason and experience. The more material he uncovered, the more difficult it was to organize the natural world into distinctly logical patterns. By placing great emphasis on experience, Gessner had amassed enough material to write four hefty volumes that far surpassed what anyone had known before about animals. But he confessed that experience alone was an undisciplined kind of knowledge. It was reason that allowed him to give some semblance of order to nature and to interpret the similarities and differences he saw among the natural things of the world.

Gessner’s methodological lessons in the midst of his Renaissance zoology remind us that the natural sciences were an important arena in which new definitions of knowledge arose from an increased emphasis on experience. In the early modern period, natural history was an important, controversial, and much discussed kind of knowledge. Natural history was a truly encyclopedic science in which broad sectors of society participated, although not, at this point, as a unified group. Learned scholars delighted in the questions of terminology that allowed them to use their formidable linguistic erudition, developing a more precise vocabulary for the natural world that conformed to their experience of it.