Plato, as regards his method of thought, was a strict and determined transcendentalist. He declared philosophy to be the science of unconditioned being, and asserted that this was known to the soul by its intuitive reason, which is the organ of all philosophic insight. The reason perceives substance, the understanding only phenomena. Being το όν, which is the reality in all actuality, is in the ideas or thoughts of God; and nothing exists or appears outwardly, except by the force of this indwelling idea. The WORD is the true expression of the nature of every object; for each has its divine and natural name, beside its accidental human appellation. Philosophy is the recollection of what the soul has seen of things and their names.
The life and essence of all things is from God. Plato's idea of God is of the purest and highest kind. God is one, he is Spirit, he is the supreme and only real being, he is the creator of all things, his providence is over all events. He avoids pantheism on one side, by making God a distinct personal intelligent will; and polytheism on the other, by making him absolute, and therefore one. Plato's theology is pure theism.[250]
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.
Zeller[256] sums up his statements on this point thus: "From all that has been said it appears that the Stoics did not think of God and the world as different beings. Their system was therefore strictly pantheistic. The sum of all real existence is originally contained in God, who is at once universal matter and the creative force which fashions matter into the particular materials of which things are made. We can, therefore, think of nothing which is not either God or a manifestation of God. In point of being, God and the world are the same, the two conceptions being declared by the Stoics to be absolutely identical."
The Stoic philosophy was materialism as regards the nature of things, and necessity as regards the nature of the human will. The Stoics denied the everlasting existence of souls as individuals, believing that at the end of a certain cycle they would be resolved into the Divine Being. Nevertheless, till that period arrives, they conceived the soul as existing in a future state higher and better than this. Seneca calls the day of death the birthday into this better world. In that world there would be a judgment on the conduct and character of each one; there friends would recognize each other, and renew their friendship and society.
While the Epicureans considered religion in all its usual forms to be a curse to mankind, while they believed it impious to accept the popular opinions concerning the gods, while they denied any Divine Providence or care for man, while they rejected prayer, prophecy, divination, and regarded fear as the foundation of religion, they yet believed, as their master Epicurus had believed, in the existence of the immortal gods. These beings he regarded as possessing all human attributes, except those of weakness and pain. They are immortal and perfectly happy; exempt from disease and change, living in celestial dwellings, clothed with bodies of a higher kind than ours, they converse together in a sweet society of peace and content.
Such were the principal theological views of the Greek philosophers. With the exception of the last, and that of the Sceptics, they were either monotheistic or consistent with monotheism. They were, on the whole, far higher than the legends of the poets or the visions of the artists. They were, as the Christian Fathers were fond of saying, a preparation for Christianity. No doubt one cause of the success of this monotheistic religion among the Greek-speaking nations was that Greek philosophy had undermined faith in Greek polytheism.