 Avempace defines this science as theoretical, the subject of which is the natural body and says that most of its subject is known by the senses (IB-SS-fakhry: 15.7–9). Physics works on the basis of principles insofar as it is theoretical and searches for causes as its demonstrative science. We should not leave aside the long discussion on the essence and position of physics in Avempace’s introduction to his Book of Animals.