=The Greek Monistic Philosophies.= Turning back to our classification on page 20, we see that the earliest Greek philosophers emphasized the monistic tendency, which had become so prominent in Greek religion. This group of monists was composed of the Milesians, Xenophanes, the Eleatic School, and Heracleitus. The course of reasoning of these early thinkers is naïvely simple, and like all naïve thought, it contains such contradictions that the modern reader is likely to become impatient with it. The value of the study of the philosophy of these early Greeks is entirely historical. Its historical value, however, is very great, for it is a revelation of the culture of the Greece of that time, it throws light on many of the teachings of Plato and Aristotle, and most of all it contains the germs of modern metaphysical problems. These first Greek philosophers raised the question, What is the constitution of the substance of the universe? Their answers are naïve solutions to the historical metaphysical “riddle.” The Milesians, who form the earliest philosophical school in European history, seem to have assumed two facts as self-evident about the substance of the universe: (1) There is a single cosmic substance identical with itself, which is the basis of all the changes in nature; (2) Moving matter is the same as life. The Milesians were quite unconscious that these two assumptions were contradictory, but the contradiction impressed their successors――Xenophanes, Heracleitus, and the Eleatics; and divided them in their development of philosophy. Matter which keeps identical with itself is the Unchanging[8] and is brought into opposition with Life, the Changing, or matter which moves. The question for Xenophanes, Heracleitus, and the Eleatics――and indeed for all future philosophy――was: How can the changing processes of life be explained by an unchanging substance?