“Many contemporary scholars see in Aristotle’s four causes only two distinct types of causes: matter (the material cause) and form (the formal cause). Aristotle’s efficient cause (work and tools) is viewed as one stage in the realization of the formal cause (the form, house to be actualized). Aristotle’s final or purposive cause is viewed as identical with the formal cause, as the purposive actualization of the house.
The enduring power of Aristotle’s principles of causality is his view that anything at all is understood only when it is seen as determined by its material cause, the matter out of which the stages of the thing have developed, and the form or pattern into which it is taking shape. We have understood the newly hatched chicken, as Aristotle’s research in his History of Animals shows us, only when we know its material cause and developmental stages in the egg and also the form of the mature hen into which it is growing. We can understand a human life, for example, Plato’s life, only when we see how the later stages of his achievements as philosopher grew out of earlier “material” stages of his family lineage, his education, his relations to Socrates, Parmenides, Heraclitus, and the Sophists, his experience of democracy, oligarchy, and war. Knowledge of the things of the world requires that we discover their genesis (material cause) and their consequences (formal cause), which connect them, through strands of complex causal linkages, with all the rest of the world.
This view of the universe, in which everything is linked causally with everything else as material or formal cause, leads Aristotle to theology and to the concept of God. A universe which is characterized throughout by eternal changes or motion requires an eternal first cause of motion which is itself unmoved. This is Aristotle’s concept of God as the Unmoved Mover, as the eternal first cause of all change or motion in the universe. Here Aristotle provides an early philosophical formulation of the cosmological proof of God’s existence, that God exists as the necessary first cause of the series of causal changes in the universe; this proof will later be employed by Saint Thomas and Descartes. In Aristotle’s theology God is an eternal actuality which causes change, and a pure actuality, since if the First Mover were material, He would be subject, like all matter, to change. Aristotle’s God is not the God of Judaism and Christianity; He is not the loving creator of the world and of man, nor is He an object of worship. Aristotle’s God is only the first cause of motion in an eternal, uncreated universe. Yet Aristotle does identify God’s pure actuality with thought or mind. What, then, are the objects of God’s thought? God cannot have objects of His thought which involve change or sensation or any kind of inferiority to Himself. Therefore, the object of God’s thought can only be Himself. God is Thought thinking Thought.”
(Lavine, From Socrates to Sartre, 72-72)