Hermes bears the same testimony, whom Cicero asserts to be reckoned by the Egyptians among the number of the gods. I speak of him who, on account of his excellence and knowledge of many arts, was called Trismegistus; and he was far more ancient not only than Plato, but than Pythagoras, and those seven wise men. In Xenophon, Socrates, as he discourses, says that the form of God ought not to be inquired about: and Plato, in his Book of Laws, says: “What God is, ought not to be the subject of inquiry, because it can neither be found out nor related.” Pythagoras also admits that there is but one God, saying that there is an incorporeal mind, which, being diffused and stretched through all nature, gives vital perception to all living creatures; but Antisthenes, in his Physics, said that there was but one natural God, although the nations and cities have gods of their own people. Aristotle, with his followers the Peripatetics, and Zeno with his followers the Stoics, say nearly the same things. Truly it would be a long task to follow up the opinions of all separately, who, although they used different names, nevertheless agreed in one power which governed the world. But, however, though philosophers and poets, and those, in short, who worship the gods, often acknowledge the Supreme God, yet no one ever inquired into, no one discussed, the subject of His worship and honours; with that persuasion, in truth, with which, always believing Him to be bounteous and incorruptible, they think that He is neither angry with any one, nor stands in need of any worship. Thus there can be no religion where there is no fear.
Source: Translated by William Fletcher. From Ante-Nicene Fathers, Vol. 7. Edited by Alexander Roberts, James Donaldson, and A. Cleveland Coxe. (Buffalo, NY: Christian Literature Publishing Co., 1886.)