"De Cetis," Icones animalium quadrupedum viviparorum et oviparorum, Zurich, C. Froschoverus, 1560 (woodcut)

In contrast to the bestiary tradition, the physician and scholar Konrad Gesner managed to re-establish the natural sciences on a recognisably scientific footing of observation, experimentation, and deduction. His encyclopedic work, compiled from folklore, ancient and medieval texts, and correspondence with a wide network of scholars, travelers, and natural philosophers, was tempered by his skepticism and an emphasis on direct observations. The combination of real and imagined natural history resulted in the inclusion of sea monsters, which Gesner classified with whales. Having never seen them himself, the images were drawn from an earlier work by Olaus Magnus who based them on seafarers’ tales.