God knows himself and only knows himself. This is the first and original knowledge, wherein he excels all creatures. No man doth exactly know himself; much less doth he understand the full nature of a spirit; much less still the nature and perfections of God; for what proportion can there be between a finite faculty and an infinite object? Herein consists the infiniteness of God’s knowledge, that he knows his own essence, that he knows that which is unknowable to anyone else. It doth not so much consist in knowing the creatures, which he hath made, as in knowing himself, who was never made. It is not so much infinite, because he knows all things which are in the world, or that shall be; or things that he can make, because the number of them is finite; but because he hath a perfect and comprehensive knowledge of his own infinite perfections. . . In fine, he could not know other things, unless he knew himself; unless he knew his own power, he could not know how he created things; unless he knew his own wisdom, he could not know the beauty of his works; unless he knew his own glory, he could not know the end of his works; unless he knew his own holiness, he could not know what was evil; and unless he knew his own justice, he could not know how to punish the crimes of his offending creatures. 

The Existence and Attributes of God (Vol. 1) - Stephen Charnock