Before somebody knows or proved that the earth is round.
It is already been said in the book of Isaiah.
Isaiah 40:22 King James Version (KJV)
22 It is he that sitteth upon 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:
The Messages (MSG)
22 God sits high above the round ball of earth.
The people look like mere ants.
He stretches out the skies like a canvasā
yes, like a tent canvas to live under.
Ferdinand Magellan proved that the earth is round in the 15th century.