Interesting that the Greeks determined the earth was round 2,400 years ago, yet 1,500 years later explorers thought it was flat

I've often wondered how everything was lost for so long.
About the same time, 2,400 years ago, the Romans came here and built brick houses, brick roads, pumped water to the buildings and pumped sewage away. Somehow, 2,000 years later people were using holes in the ground again.

Just stumbled across something else. The ancient Egyptians had some relatively successful methos of anaesthetic 3,500 years ago. All that was lost until 200 years ago.