Historia animalium ("History of the Animals"), published at Zurich in 1551–58 and 1587, is an encyclopedic "inventory of renaissance zoology" by Conrad Gessner (1516–1565). Gessner was a medical doctor and professor at the Carolinum in Zürich, the precursor of the University of Zurich. The Historia animalium is the first modern zoological work that attempts to describe all the animals known, and the first bibliography of natural history writings. The five volumes of natural history of animals cover more than 4500 pages.
There was extreme religious tension at the time Historia animalium came out. Under Pope Paul IV it was felt that the religious convictions of an author contaminated all his writings, and as Gessner was a protestant, it was added to the Catholic Church's list of prohibited books.
The Historia animalium was Gessner's magnum opus, and was the most widely read of all the Renaissance natural histories. The work was so popular that Gessner's abridgement, Thierbuch ("Animal Book"), was published in Zurich in 1563, and in England Edward Topsell translated and condensed it as a Historie of foure-footed beastes (London: William Jaggard, 1607). Gessner’s monumental work attempts to build a connection between the ancient knowledge of the animal world, its title the same as Aristotle's work on animals, and what was known at his time. He then adds his own observations, and those of his correspondents, in an attempt to formulate a comprehensive description of the natural history of animals.
Gessner’s Historia animalium is based on classical sources. It is compiled from ancient and medieval texts, including the inherited knowledge of ancient naturalists like Aristotle, Pliny the Elder, and Aelian. Gessner was known as "the Swiss Pliny." For information he relied heavily on the Physiologus.