And this is proved to us, not only by argument, but by the wisest and most ancient of the Hebrews, so far as they have given us reason for conjecture.
For they appropriated certain characters to the honour of the Deity, and would not even allow the name of anything inferior to God to be written with the same letters as that of God.
Because to their minds it was improper that the Deity should even to that extent admit any of His creatures to a share with Himself.
How then could they have admitted that the invisible and separate Nature can be explained by divisible words?
For neither has any one yet breathed the whole air, nor has any mind entirely comprehended, or speech exhaustively contained the Being of God.
But we sketch Him by His Attributes, and so obtain a certain faint and feeble and partial idea concerning Him.
And our best Theologian is he who has, not indeed discovered the whole, for our present chain does not allow of our seeing the whole.
Our best Theologian is he who has conceived of Him to a greater extent than another, and gathered in himself more of the Likeness or adumbration of the Truth, or whatever we may call it.
As far then as we can reach, He Who Is, and God, are the special names of His Essence, and of these especially He Who Is:
not only because when He spake to Moses in the mount, and Moses asked what His Name was, this was what He called Himself, bidding him say to the people “I Am hath sent me” (Exod. I3:14), but also because we find that this Name is the more strictly appropriate.
For the Name Θεός (God), even if, as those who are skilful in these matters say, it were derived from Θέειν (to run) or from Αἴθειν (to blaze), from continual motion, and because He consumes evil conditions of things – from which fact He is also called A Consuming Fire (Deut. 4:24) – would still be one of the Relative Names, and not an Absolute one.
This is also the case with Lord, which also is called a name of God. I am the Lord Thy God, He says, that is My name (Isa. 42:8); and, The Lord is His name (Amos 9:6).
But we are enquiring into a Nature Whose Being is absolute and not into Being bound up with something else.
But Being is in its proper sense peculiar to God, and belongs to Him entirely, and is not limited or cut short by any Before or After, for indeed in him there is no past or future.
Gregory Nazianzen (c.330-390): Oration 30, 17-18 (slightly adapted).