But five hundred years ago ancient Greeks hadn't lived for centuries already.
They (Italians and other Europeans) still knew the Earth was round. Indeed, if you live near a sea port this is a very easy thing to figure out. The resistance Columbus faced was that everyone thought the world was much too big to get to the Indies in a reasonable period of time by sailing west. And of course everyone was right and Columbus had no idea what he was talking about.
Edit: And actually I'm pretty sure the authorities cerca 1492 were basing their beliefs about the size of the Earth on work done by the ancient Greeks.
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.