Cosmas Indicopleustes

And with regard to the earth it is again written in Job: He that hangeth the earth upon nothing; meaning, that it had nothing underneath it. And David in harmony with this, when he could discover nothing on which it was founded, says: He that hath founded the earth upon its own stability, as if he said, it hath been founded by thee upon itself, and not upon anything else.

The Christian Topography, Book 4 ↗

Gregory the Dialogist

He stretcheth out the north over the empty place. [MYSTICAL INTERPRETATION] By the title of the 'north,' in Holy Writ the devil is used to be designated, who with the thought to bind up the hearts of the nations with the iciness of insensibility, said, I will sit also upon the mount of the Covenant, in the sides of the north. And he is 'stretched over the empty place,' because he has possession of those hearts, that are not filled with the grace of the love of God. …

Morals on the Book of Job, Book XVII ↗

Thomas Aquinas

Then he lists the effects of divine providence in natural things, and he begins from the two extremes, from earth and heaven. In each of these something appears instituted from divine power which exceeds human strength. As far as what appears to the senses, heaven seems to be extended above the earth like a kind of tent; earth to be under heaven like the floor of the tent. Whoever sets up a tent puts something by which the tent can be supported. This does not seem to be the case with heaven. …

Commentary on Job ↗