 The Arabic word falsafah is taken from the Greek philosophia. Falsafah is understood by our authors as an intellectual practice developed in Ancient Greece, which emphasizes the use of rational understanding and demonstration in the pursuit of knowledge (ʿilm). For them, the most important and influential of the Ancient Greek philosophers is Aristotle, whom they deem “the First Teacher”. Other influences include Neoplatonic thinkers, especially Proclus and Plotinus, as well as Ancient Greek commentators on Aristotle, such as Alexander of Aphrodisias. See the entry on  Greek sources in Arabic and Islamic philosophy.