scrutinizes them for consistency. Socrates criticized the older type of study of physics as too purely speculative and lacking in self-criticism. Aristotle in the 4th century BCE created a systematic program of teleological philosophy. In the 3rd century BCE, Greek astronomer Aristarchus of Samos was the first to propose a heliocentric model of the universe, with the Sun at the center and all the planets orbiting it. Aristarchus's model was widely rejected because it was believed to violate the laws of physics, while Ptolemy's Almagest, which contains a geocentric description of the Solar System, was accepted through the early Renaissance instead. The inventor and mathematician Archimedes of Syracuse made major contributions to the beginnings of calculus. Pliny the Elder was a Roman writer and polymath, who wrote the seminal encyclopedia Natural History. Middle Ages Due to the collapse of the Western Roman Empire, the 5th century saw an intellectual decline and knowledge of Greek conceptions of the world deteriorated in Western Europe. During the period, Latin encyclopedists such as Isidore of Seville preserved the majority of general ancient knowledge. In contrast, because the Byzantine Empire resisted attacks from invaders, they were able to preserve and improve prior learning. John Philoponus, a Byzantine scholar in the 500s, started to question Aristotle's teaching of physics, introducing the theory of impetus. His criticism served as an inspiration to medieval scholars and Galileo Galilei, who extensively cited his works ten centuries later. During late antiquity and the early Middle Ages, natural phenomena were mainly examined via the Aristotelian approach. The approach includes Aristotle's four causes: material, formal, moving, and final cause. Many Greek classical texts were preserved by the Byzantine empire and Arabic translations were done by groups such as the Nestorians and the Monophysites. Under the Caliphate, these Arabic translations were later improved and developed by Arabic scientists. By the 6th and 7th centuries, the neighboring Sassanid Empire established the medical Academy of Gondeshapur, which is considered by Greek, Syriac, and Persian physicians as the most important medical center of the ancient world. The House of Wisdom was established in Abbasid-era Baghdad, Iraq, where the Islamic study of Aristotelianism flourished until the Mongol invasions in the 13th century. Ibn al-Haytham, better known as Alhazen, began experimenting as a means to gain knowledge and disproved Ptolemy's theory of vision Avicenna's compilation of the Canon of Medicine, a medical encyclopedia, is considered to be one