Greek Philosophy

After reading part one of the book “Greek Philosophy:Thales to Aristotle”, explain why it is said that the Pre-Socrates were “Naturalists” and by extension “Materialists.” In what sense did Thales produce the first scientific Grand Unified Theory of everything, while explaining the nations Unity, Monism, Reductionism, Naturalism, Immanence, Rationalism, Neccessitariasm, and Logos? What is the major reason philosophy is generaly thought to begin with the pre-socratics?