Ancient 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. One scholar has noted, "Western philosophy is just a series of footnotes to Plato.
In many ways, it has had an important influence on modern philosophy, as well as modern science. Clear unbroken lines of influence lead from ancient Greek and Hellenistic philosophers, to medieval Muslim philosophers and scientists, to the European Renaissance and Enlightenment, to the secular sciences of the modern day.
The presocratics were primarily ontologists who rejected mythological explanations for 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.
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 Western thought. 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. Aristotle began his own school, the Academy. He also taught Alexander the Great.
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: early Islamic philosophy, Jewish philosophy and Christian 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..