=3. Aristotle’s Conception of God.= In the Aristotelian system the assumption of an upper final term of pure Form was necessary, because Matter as the possible and potential is not endowed with the power of motion and generation. To Aristotle development is not a process with temporal beginning and ending, but is a kind of closed circuit. Since reality is in itself a developing essence, motion is as eternal as reality. We should not ask, therefore, When did the world begin, and when will it end? but we can legitimately ask, What is the nature of reality that keeps motion alive? When we examine individual things, we find, according to Aristotle’s explanation, that motion is the result of the influence of Form upon Matter. There is inherent in matter an impulse to be formed, and there is inherent in Form an active forming purpose. But we may search individual things in vain for the causal explanation of motion, since every Form is in turn the Matter for a higher Form. The chain would be endless and not intelligible if there did not exist a pure Form, which is unmoved. God as the unmoved mover is the cause of the world-motion, but God must be the cause in a different sense from the physical causes, which are themselves moved. God operates as a cause upon Matter, not as a mechanical cause but as pure Form,――as a final or teleological cause. God is the cause in the sense that God excites in Matter the impulse to be actual, like God. This prime mover is similar to Plato’s Idea of the Good. _As to its form_ it is eternal, unmovable, unchangeable, wholly independent and incorporeal, and yet the cause of all generation and change. God is the perfect Being in whom all possibility is actuality. _As to its content_ God is pure thought. But in respect to his thought God is not like human thought, which is concerned with external phenomena and changing things. God is thought that has nothing else for its object than itself and its own unchanging content. God is “thought of thought.” God’s contemplation of himself is his own blessed life. Here in Aristotle is a momentous conception formed for the first time in the history of thought. Monotheism is for the first time conceptually framed and scientifically grounded. The monism of Aristotle’s predecessors passes over into a theism. God is not only immaterial in the sense that Plato defined the Ideas, but he is spiritual. In Aristotle’s transcendent God, conceived as pure self-consciousness, we have the ripest fruit of Greek philosophy.