tried to explain the world with characteristics found within this world. Systematic because they tried to universalize their findings. Economical because they tried to invoke only a few new terms. Based on these features, they reached their most significant achievement, they changed the course of human thought from myth to philosophy and science. The pre-Socratics were not atheists; however, they minimized the extent of the gods' involvement in natural phenomena such as thunder or totally eliminated the gods from the natural world. Pre-Socratic philosophy encompasses the first of the three phases of ancient Greek philosophy, which spanned around a thousand years. The pre-Socratic phase itself is divided into three phases. The first phase of pre-Socratic philosophy, mainly the Milesians, Xenophanes, and Heraclitus, consisted of rejecting traditional cosmogony and attempting to explain nature based on empirical observations and interpretations. A second phase – that of the Eleatics – resisted the idea that change or motion can happen. Based on their radical monism, they believed that only one substance exists and forms Kosmos. The Eleatics were also monists (believing that only one thing exists and everything else is just a transformation of it). In the third phase, the post-Eleatics (mainly Empedocles, Anaxagoras, and Democritus) opposed most Eleatic teaching and returned to the naturalism of the Milesians. The pre-Socratics were succeeded by the second phase of ancient philosophy, where the philosophical movements of Platonism, Cynicism, Cyrenaicism, Aristotelianism, Pyrrhonism, Epicureanism, Academic skepticism, and Stoicism rose to prominence until 100 BCE. In the third phase, philosophers studied their predecessors. Pre-Socratic philosophers Milesian beginning: Thales, Anaximander and Anaximenes The Milesian school was located in Miletus, Ionia, in the 6th century BCE. It consisted of Thales, Anaximander, and Anaximenes, who most probably had a teacher-pupil relationship. They were mainly occupied with the origin and substance of the world; each of them attributed the Whole to a single arche (beginning or principle), starting the tradition of naturalistic monism. Thales Thales (c. 624–546 BCE) is considered to be the father of philosophy. None of his writings have survived. He is considered the first western philosopher since he was the first to use reason, to use proof, and to generalize. He created the word cosmos, the first word to describe the universe. He contributed to geometry and predicted the eclipse of 585 BCE. Thales may have been of Phoenician ancestry. Miletus was a meeting point and trade centre of the