Continuing with the theme of what can be known of God apart from Revelation, I now want to turn to three beliefs which are absolutely fundamental to Aquinas's thinking. These are: (1) God is everywhere; (2) God is unchangeable; (3) God is eternal. When we have seen what Aquinas has to say in presenting and defending these theses, we shall, in Chapters 7 and 8 , consider his teaching on seven further related topics: God's oneness, power, knowledge, will, love, justice, and mercy.
The belief that God is everywhere, sometimes known as the doctrine of divine ubiquity, has always been part and parcel of Judeo-Christian theism. So it is hardly surprising that Aquinas subscribes to it. As a Dominican friar he would often have chanted the words of Psalm 139:
Whither shall I go from thy Spirit?
Or whither shall I flee from thy presence?
If I ascend to heaven, thou art there!
If I make my bed in Sheol, thou art there!
In his scheme of things, however, belief in God's omnipresence takes on a special importance. For he invokes it constantly, and it is much more prominent in his system that it is in the thinking of many other theistic writers. As he understands it, it also means something different from what it does to some theists. For he does not think that God is present just in the sense of knowing what is going on everywhere and being able to interfere. He thinks that God exists in everything and is in every place. He also thinks that God is wholly in everything and that being everywhere only applies to God.
The intellectual foundation of his position here lies in something