A metaphor to mull over

This is a false statement. The curvature of the earth *is* visible from a sufficiently high point. There are numerous mountains where you could, with rather crude tools, easily detect this.

But they where back in the 15th century, and the people arguing this theories were Europeans and the higher mountains they could access were the alpes (don't really know their English name, the mountains north of Italy), and their methods were not accurate as far as I know. Not until galileo galilei I guess.