According To The Teaching of St. Thomas Aquinas
PART FIRST.
THE ORDINARY PRESENCE OF GOD IN ALL CREATURES ³
And if you question the Angelic Doctor as to how God, an immaterial, unextended and indivisible substance, can be present in all places, and in the inner depths of beings occupying material space, he will answer you with a comparison borrowed from nature and already employed by the Fathers, namely: He is present in three ways: "By His power, by His presence, and by His essence. By His power, because all things are subject to His sovereign command: He is present everywhere like a king who, while residing in his palace, is by a fiction deemed present in all the parts of his kingdom where he exercises authority. By His presence, that is to say most intimately, because He knows all things and sees all things; and nothing, however hidden it may be, can escape His attention; all things are present to Him as objects are said to be in our presence, although they may be situated at a slight distance from our person. Finally by His essence, for He is as really and in His very substance present to all created things as a monarch is present in person to the throne on which he is seated." (Summa Theologica, I., q. viii., a. 3.)
The reason for this substantial presence of God in His creatures is that not one of them could dispense with the divine action preserving its existence and actuating its operations; and since substance and action are not really distinct in God, it follows that "He is substantially—in His actual reality—present wherever He works, i.e., in all things and in all places." (Summa Theologica, I., q. viii., a. 1.)
