John of Damascus De fide orth 1.4

It is plain, then, that there is a God. But what He is in His essence and nature is absolutely incomprehensible and unknowable. For it is evident that He is incorporeal. For how could that possess body which is infinite, and boundless, and formless, and intangible and invisible, in short, simple and not compound? How could that be immutable which is circumscribed and subject to passion? And how could that be passionless which is composed of elements and is resolved again into them? For combination is the beginning of conflict, and conflict of separation, and separation of dissolution, and dissolution is altogether foreign to God.

Again, how will it also be maintained that God permeates and fills the universe? As the Scriptures say, Do not I fill heaven and earth, says the Lord Jeremiah 23:24? For it is an impossibility that one body should permeate other bodies without dividing and being divided, and without being enveloped and contrasted, in the same way as all fluids mix and commingle.

But if some say that the body is immaterial, in the same way as the fifth body of which the Greekphilosophers speak (which body is an impossibility), it will be wholly subject to motion like the heaven. For that is what they mean by the fifth body. Who then is it that moves it? For everything that is moved is moved by another thing. And who again is it that moves that? And so on to infinity till we at length arrive at something motionless. For the first mover is motionless, and that is the Deity. And must not that which is moved be circumscribed in space? The Deity, then, alone is motionless, moving the universe by immobility. So then it must be assumed that the Deity is incorporeal.

But even this gives no true idea of His essence, to say that He is unbegotten, and without beginning, changeless and imperishable, and possessed of such other qualities as we are wont to ascribe to God and His environment. For these do not indicate what He is, but what He is not. But when we would explain what the essence of anything is, we must not speak only negatively. In the case of God, however, it is impossible to explain what He is in His essence, and it befits us the rather to hold discourse about His absolute separation from all things. For He does not belong to the class of existing things: not that He has no existence , but that He is above all existing things, nay even above existence itself. For if all forms of knowledge have to do with what exists, assuredly that which is above knowledge must certainly be also above essence : and, conversely, that which is above essence will also be above knowledge.

God then is infinite and incomprehensible and all that is comprehensible about Him is His infinity and incomprehensibility. But all that we can affirm concerning God does not show forth God’s nature, but only the qualities of His nature. For when you speak of Him as good, and just, and wise, and so forth, you do not tell God’s nature but only the qualities of His nature. Further there are some affirmations which we make concerning God which have the force of absolute negation: for example, when we use the term darkness, in reference to God, we do not mean darkness itself, but that He is not light but above light: and when we speak of Him as light, we mean that He is not darkness.