Secondly, truth is saving truth, and Manichaeism is a system of salvation. The elements of the good, which are captivated by the evil principle, are saved from it. This makes it attractive for Augustine because salvation is his main question. Thirdly, truth is in the struggle between good and bad, ,which gives him a possibility of interpreting history. Now he remained always, somehow, under the at least coloring influence of Manichaeism. He was not a Manichaean any more, after he left the group; he fought against it. But something in his thinking and even more, in his feeling, was colored by the profound pessimism about reality… His doctrine of sin is probably not understandable without his Manichaean period.
But he left Manichaeism, under the influence of astronomy. Astronomy showed him the perfect motion of the stars, i. e., the fundamental elements in the structure of the universe. This made a dualistic principle almost impossible. If the structure of the universe is a structure of regular mathematical forms which can be calculated and which are harmonius, where can you find the effect of the demonic creation in the world? The world as created in its basic structure is good – this is what he derived from it. This means he uses the Greek Pythagorean idea of the cosmos. He used the principle of form and harmony as it was expressed in mathematics.
Now this Greek European principle overcame the Asiatic dualism and negativity. So the separation of Augustine from the Manichaean philosophy was a symbolic event.
It was the liberation of modern natural science, mathematics and technics from the Asiatic dualistic pessimism and negation of reality. This was extremely important for the future of Europe. And, as we shall see, as far as we have time to see it, the later medieval Augustinian philosophers and theologians were always men who emphasized astronomy and mathematics more than anything else. Modern natural science is born, as are Platonism and Augustinianism, on the basis of a belief in a harmonious cosmos determined by mathematical rules. This was also the worldview of the Renaissance. So if we look deeper into the movements of thought, then this anecdotic story, that AugustIne left the Manichaeans because of astronomy and that he had joined them because of the explanation of sin and evil, becomes a world-historical symbol for the relationship of the East and the West, of the Asiatic East and the European West.