The doctrine of the sphericity of the earth naturally led to thought regarding its inhabitants, and another ancient germ was warmed into life--the idea of antipodes: of human beings on the earth's opposite sides.
In the Greek and Roman world this idea had found supporters and opponents, Cicero and Pliny being among the former, and Epicurus, Lucretius, and Plutarch among the latter.

Thus the problem came into the early Church unsolved.
Among the first churchmen to take it up was, in the East, St.Gregory Nazianzen, who showed that to sail beyond Gibraltar was impossible; and, in the West, Lactantius, who asked: "Is there any one so senseless as to believe that there are men whose footsteps are higher than their heads ?...

that the crops and trees grow downward ?...

that the rains and snow and hail fall upward toward the earth ?...

I am at a loss what to say of those who, when they have once erred, steadily persevere in their folly and defend one vain thing by another." In all this contention by Gregory and Lactantius there was nothing to be especially regretted, for, whatever their motive, they simply supported their inherited belief on grounds of natural law and probability.
Unfortunately, the discussion was not long allowed to rest on these scientific and philosophical grounds; other Christian thinkers followed, who in their ardour adduced texts of Scripture, and soon the question had become theological; hostility to the belief in antipodes became dogmatic.