Greek philosophy focused on the role of reason and inquiry. Many philosophers today concede that Greek philosophy has shaped the entire Western thought since its inception. As Alfred Whitehead once noted, with some exaggeration, "Western philosophy is just a series of footnotes to Plato." Clear, unbroken lines of influence lead from ancient Greek and Hellenistic philosophers, to medieval Islamic philosophers, to the European Renaissance and Enlightenment.
Some claim that Greek philosophy, in turn, was influenced by the older wisdom literature and mythological cosmogonies of the ancient Near East. According to Martin Litchfield West: "[...]contact with oriental cosmology and theology helped to liberate their [the early Greek philosophers'] imagination; it certainly gave them many suggestive ideas. But they taught themselves to reason. Philosophy as we understand it is a Greek creation."
Neither reason nor inquiry began with the Ancient Greeks, but the Socratic method, along with the idea of Forms, allowed great advances in geometry, logic, and the natural sciences. Defining the difference between the Ancient Greek quest for knowledge and the quests of the elder civilizations, such as the ancient Egyptians and Babylonians, has long been a topic of study by theorists of civilization. Benjamin Farrington, former Professor of Classics at Swansea University, wrote:
The presocratics were primarily ontologists who rejected mythological explanations in favor of reasoned discourse. Parmenides, for example, gave one of the first documented logical arguments: How could what is perish? How could it have come to be? For if it came into being, it is not; nor is it if ever it is going to be. Thus coming into being is extinguished, and destruction unknown.
Heraclitus, in contrast to Parmenides' immutable one, asserted that the only thing that doesn’t change and perish is change itself. As can be seen, then, the presocratics were concerned with what exists, where it comes from, what it comes from, how it exists and how the plurality of natural objects can be explained.
Leucippus, against the monism of Parmenides, proposed an ontological pluralism with a cosmogony based on two main elements: the vacuum and atoms. These, by means of their inherent movement, are crossing the void and creating the real material bodies.
Aristotle, Aristoteles in Latin and many other languages (but Aristote in French and Aristotele in Italian), (384 BC - 322 BC) has, along with Plato, the reputation of one of the most influential philosophers in history. Their works, although connected in many fundamental ways, differ considerably in both style and substance. Plato wrote several dozen philosophical dialogues—arguments in the form of conversations, usually with Socrates as a participant—and a few letters. Though the early dialogues deal mainly with methods of acquiring knowledge, and most of the last ones with justice and practical ethics, his most famous works expressed a synoptic view of ethics, metaphysics, reason, knowledge, and human life. Predominant ideas include the notion that knowledge gained through the senses always remains confused and impure, and that the contemplative soul that turns away from the world can acquire "true" knowledge. The soul alone can have knowledge of the Forms, the real essences of things, of which the world we see is but an imperfect copy. Such knowledge has ethical as well as scientific import. One can view Plato, with qualification, as an idealist and a rationalist.
Aristotle was one of Plato's students, but placed much more value on knowledge gained from the senses, and would correspondingly better earn the modern label of empiricist. Thus Aristotle set the stage for what would eventually develop into the scientific method centuries later. The works of Aristotle that still exist today appear in treatise form, mostly unpublished by their author. The most important include Physics, Metaphysics, (Nicomachean) Ethics, Politics, De Anima (On the Soul), Poetics, and many others.
Aristotle was a great thinker and philosopher, and was called 'the Master' by Avicenna in the following centuries and 'the Philosopher' by others, since his philosophy was crucial in governing intellectual thought in the Western world. His views and approaches dominated early Western science for almost 2000 years. As well as philosophy, Aristotle was a formidable inventor, and is credited with many significant inventions and observations. He also tutored Alexander the Great.
During the Hellenistic and Roman periods, many different schools of thought developed in the Hellenistic world and then the Greco-Roman world. There were Greeks, Romans, Egyptians, Syrians and Arabs who contributed to the development of Hellenistic philosophy. Elements of Persian philosophy and Indian philosophy also had an influence. The most notable schools of Hellenistic philosophy were:
The spread of Christianity throughout the Roman world, followed by the spread of Islam, ushered in the end of Hellenistic philosophy and the beginnings of Medieval philosophy, which was dominated by the three Abrahamic traditions: Jewish philosophy, Christian philosophy, and early Islamic philosophy.
During the Middle Ages, Greek ideas were largely forgotten in Western Europe. With the fall of Rome, very few people in the West were left who knew how to read Greek. The Islamic Abbasid caliphs gathered the manuscripts and hired translators to increase their prestige. Islamic philosophers such as Al-Kindi (Alkindus), Al-Farabi (Alpharabius), Avicenna (Ibn Sina) and Averroes (Ibn Rushd) reinterpreted Greek philosophies in the context of their religion. Their interpretations were later transmitted to the Europeans in the High Middle Ages, when Greek philosophies re-entered the West through translations from Arabic to Latin. The re-introduction of these philosophies, combined with the new Arabic commentaries, had a great influence on Medieval philosophers such as Thomas Aquinas.