Erasistratus of Chios—amended Aristotle's physiological work, even performing experimental dissections and vivisections. Claudius Galen became the most important authority on medicine and anatomy. Though a few ancient atomists such as Lucretius challenged the teleological Aristotelian viewpoint that all aspects of life are the result of design or purpose, teleology (and after the rise of Christianity, natural theology) remained central to biological thought until the 18th and 19th centuries. Medieval and Islamic zoology The decline of the Roman Empire led to the disappearance or destruction of much knowledge, though physicians still incorporated many aspects of the Aristotelian tradition into training and practice. In Byzantium and the Islamic world, many of Aristotle's works were translated into Arabic and commented upon by scholars such as Avicenna and Averroes. Medieval Muslim physicians, scientists and philosophers made significant contributions to zoological knowledge between the 8th and 13th centuries during the Islamic Golden Age. The Arab scholar al-Jahiz (781–869) described early evolutionary ideas such as the struggle for existence. He also introduced the idea of a food chain, and was an early adherent of environmental determinism. During the High Middle Ages, a few European scholars such as Hildegard of Bingen, Albertus Magnus and Frederick II expanded the natural history canon. Magnus's De animalibus libri XXVI was one of the most extensive studies of zoological observation published before modern times. Renaissance and early modern From anatomy to systematic taxonomy The Renaissance was the age of collectors and travellers, when many of the stories were actually demonstrated as true when the living or preserved specimens were brought to Europe. Verification by collecting of things, instead of the accumulation of anecdotes, then became more common, and scholars developed a new faculty of careful observation. The Renaissance brought expanded interest in both empirical natural history and physiology. In 1543, Andreas Vesalius inaugurated the modern era of Western medicine with his seminal human anatomy treatise De humani corporis fabrica, which was based on dissection of corpses. Vesalius was the first in a series of anatomists who gradually replaced scholasticism with empiricism in physiology and medicine, relying on first-hand experience rather than authority and abstract reasoning. Bestiaries—a genre that combines both the natural and figurative knowledge of animals—also became more sophisticated. Conrad Gessner great zoological work, Historiae animalium, appeared in four volumes, 1551–1558, at Zürich, a fifth being issued in 1587. His works were the starting-point of modern zoology. Other major works