The World Is Not Flat
While everybody now knows that the world is a sphere, it is a relatively recent idea in the history of humanity, along with being a great and hard fought victory for reason. For tens of thousands of years, people generally thought that the earth was flat, having observed the apparent horizontal nature of the ground that they stood on. Still, some inconvenient truths appeared to be incongruous with the flat earth theory. For example, why did the sun rise in the east and set in the west day after day? Why do the stars appear to move in a circular direction around the night sky?