Ackermann, in "The Christian Element in Plato,"[251] says: The Platonic theology is strikingly near that of Christianity in regard to God's being, existence, name, and attributes. As regards the existence of God, he argues from the movements of nature for the necessity of an original principle of motion.[252] But the real Platonic faith in God, like that of the Bible, rests on immediate knowledge. He gives no definition of the essence of God, but says,[253] "To find the Maker and Father of this All is hard, and having found him it is impossible to utter him." But the idea of Goodness is the best expression, as is also that of Being, though neither is adequate. The visible Sun is the image and child of the Good Being. Just so the Scripture calls God the Father of light. Yet the idea of God was the object and aim of his whole philosophy; therefore he calls God the Beginning and the End;[254] and "the Measure of all things, much more than _man_, as some people have said" (referring to Protagoras, who taught that "man was the measure of all things"). So even Aristotle declared that "since God is the ground of all being, the first philosophy is theology"; and Eusebius mentions that Plato thought that no one could understand human things who did not first look at divine things; and tells a story of an Indian who met Socrates in Athens and asked him how he must begin to philosophize. He replied that he must reflect on human life; whereupon the Indian laughed and said that as long as one did not understand divine things he could know nothing about human things. There is no doubt that Plato was a monotheist, and believed in one God, and when he spoke of gods in the plural, was only using the common form of speech. That many educated heathen were monotheists has been sufficiently proved; and even Augustine admits that the mere use of the word "gods" proved nothing against it, since the Hebrew Bible said, "the God of gods has spoken." Aristotle (B.C. 384), the first philologian and naturalist of antiquity, scholar of Plato, called "the Scribe of Nature," and "a reversed Plato," differing diametrically from his master in his methods, arrived at nearly the same theological result. He taught that there were first truths, known by their own evidence. He comprised all notions of existence in that of the κόσμος, in which were the two spheres of the earthly and heavenly. The earthly sphere contained the changeable in the transient; the heavenly sphere contained the changeable in the permanent. Above both spheres is God, who is unchangeable, permanent, and unalterable. Aristotle, however, omits God as Providence, and conceives him less personally than is done by Plato. In the Stoical system, theism becomes pantheism.[255] There is one Being, who is the substance of all things, from whom the universe flows forth, and into whom it returns in regular cycles.