“But the nature of man,” it is said, “is narrow and circumscribed, whereas the Deity is infinite. How could the infinite be included in the atom?” But who is it that says the infinitude of the Deity is comprehended in the envelopment of the flesh as if it were in a vessel? Not even in the case of our own life is the intellectual nature shut up within the boundary of the flesh. On the contrary, while the body's bulk is limited to the proportions peculiar to it, the soul by the movements of its thinking faculty can coincide at will with the whole of creation.
It ascends to the heavens, and sets foot within the deep. It traverses the breadth of the world, and in the restlessness of its curiosity makes its way into the regions that are beneath the earth; and often it is occupied in the scrutiny of the wonders of heaven, and feels no weight from the appendage of the body. If, then, the soul of man, although by the necessity of its nature it is transfused through the body, yet presents itself everywhere at will, what necessity is there for saying that the Deity is hampered by an environment of fleshly nature, and why may we not, by examples which we are capable of understanding, gain some reasonable idea of God's plan of salvation?
There is an analogy, for instance, in the flame of a lamp, which is seen to embrace the material with which it is supplied. Reason makes a distinction between the flame upon the material, and the material that kindles the flame, though in fact it is not possible to cut off the one from the other so as to exhibit the flame separate from the material, but they both united form one single thing. But let no one, I beg, associate also with this illustration the idea of the perishableness of the flame; let him accept only what is apposite in the image; what is irrelevant and incongruous let him reject.
What is there, then, to prevent our thinking (just as we see flame fastening on the material, and yet not inclosed in it) of a kind of union or approximation of the Divine nature with humanity, and yet in this very approximation guarding the proper notion of Deity, believing as we do that, though the Godhead be in man, it is beyond all circumscription?
Source: The Great Catechism (New Advent)