Hilary of Poitiers

The words “I AM THAT I AM” were clearly an adequate indication of God’s infinity. But, in addition, we needed to apprehend the operation of his majesty and power. For while absolute existence is peculiar to him who, abiding eternally, had no beginning in a past however remote, we hear again an utterance worthy of himself issuing from the eternal and holy God, who says, “who holds the heaven in his palm and the earth in his hand,” and again, “The heaven is my throne and the earth is the footstool of my feet. What house will you build me or what shall be the place of my rest?” The whole heaven is held in the palm of God, the whole earth grasped in his hand.Now the word of God … reveals a deeper meaning to the patient student.… This heaven that is held in the palm of God is also his throne, and the earth that is grasped in his hand is also the footstool beneath his feet. This was not written that … we should conclude that he has extension in space, as of a body.… It was written that in all born and created things God might be known within them and without, overshadowing and indwelling, surrounding all and interfused through all, since palm and hand, which hold, reveal the might of his external control, while throne and footstool, by their support of a sitter, display the subservience of outward things to One who, himself outside them, encloses all in his grasp.… Being infinite, he is present in all things. In him who is infinite all are included.

The words “I am that I am” were clearly an adequate indication of God’s infinity. But, in addition, we needed to apprehend the operation of his majesty and power. For while absolute existence is peculiar to him who, abiding eternally, had no beginning in a past however remote, we hear again an utterance worthy of himself issuing from the eternal and holy God, who says, “who holds the heaven in his palm and the earth in his hand,” and again, “The heaven is my throne and the earth is the footstool of my feet. What house will you build me or what shall be the place of my rest?” The whole heaven is held in the palm of God, the whole earth grasped in his hand.
Now the word of God … reveals a deeper meaning to the patient student.… This heaven that is held in the palm of God is also his throne, and the earth that is grasped in his hand is also the footstool beneath his feet. This was not written that … we should conclude that he has extension in space, as of a body.… It was written that in all born and created things God might be known within them and without, overshadowing and indwelling, surrounding all and interfused through all, since palm and hand, which hold, reveal the might of his external control, while throne and footstool, by their support of a sitter, display the subservience of outward things to One who, himself outside them, encloses all in his grasp.… Being infinite, he is present in all things. In him who is infinite all are included. - "On the Trinity 1.6"

But it may be argued that the apostle was not inspired by the Spirit of prophecy when he borrowed these prophetic words; that he was only interpreting at random the words of another man, and though, no doubt, everything the apostle says of himself comes to him by revelation from Christ, yet his knowledge of the words of Isaiah is only derived from the book.… Isaiah says that he has seen no God besides him. For he did actually see the glory of God, the mystery of whose taking flesh from the Virgin he foretold. And if you, in your heresy, do not know that it was God the Only Begotten whom the prophet saw in that glory, listen to the Evangelist: “Isaiah said these things when he saw his glory and spoke of him.” The apostle, the Evangelist, the prophet combine to silence your objections. Isaiah did see God; even though it is written, “No one has seen God at any time, except for the only-begotten Son who is in the bosom of the Father; he has declared him.” It was God whom the prophet saw. He gazed on the divine glory, and people were filled with envy at such honor graciously granted to his prophetic greatness. For this was the reason why the Jews passed sentence of death on him.