Charles Ellicott Commentary Isaiah 40:22

"[It is] he that sitteth above the circle of the earth, and the inhabitants thereof are as grasshoppers; that stretcheth out the heavens as a curtain, and spreadeth them out as a tent to dwell in;" — Isaiah 40:22 (ASV)

The circle of the earth — that is, the vault of heaven overarching the earth (Job 22:14; Proverbs 8:27).

As grasshoppers. — The word indicates some insect of the locust tribe. The comparison may have been suggested by Numbers 13:33.

That stretches out the heavens. — A favorite phrase of 2 Isaiah (Isaiah 42:5; Isaiah 44:24; and others), taken probably from Psalms 104:2.

As a curtain ... as a tent. — The words indicate a clearer perception of space than the older Hebrew word for the “firmament” of Genesis 1:7. The visible heavens are thought of as a thin, filmy veil of gauze, the curtains of the tent of God.