Greek philosophy focused on the role of reason and inquiry. In many ways, it had an important influence on modern philosophy, as well as modern science.
The pre-Socratic 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.
An Arab's depiction of Socrates teaching his students.
During the Middle Ages, Greek ideas were largely forgotten in Europe. With the fall of Rome, very few people in the west were left who knew how to read Greek.
Greek philosophies were kept alive at this time by Arabs, who hired Syriac Christians to translate from Greek into Arabic. Many Islamic rulers gathered the manuscripts and hired translators to increase their prestige.
Hellenistic philosophy is the period of Western philosophy that was developed in the Hellenistic civilization.
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.