Because of the collapse of the Western Roman Empire due to the Migration Period an intellectual decline took place in the western part of Europe in the 400s. In contrast, the Byzantine Empire resisted the attacks from invaders, and preserved and improved upon the learning. John Philoponus, a Byzantine scholar in the 500s, questioned Aristotle's teaching of physics and to note its flaws.[56]:pp.307, 311, 363, 402 John Philoponus' criticism of Aristotelian principles of physics served as an inspiration to medieval scholars as well as to Galileo Galilei who ten centuries later, during the Scientific Revolution, extensively cited Philoponus in his works while making the case for why Aristotelian physics was flawed.[56][57]