People tend to think that people who lived hundreds of years before us were stupid because they didn't have our technology and were superstitious. Humanity has always been the same.
I have found that it is futile to have a battle of wits with a witless person.
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I imagine it would be close to walking on sand; you would probably leave a small depression, but not sink. While it is liquid, it's still rock. I'll leave to someone better in physics to do the math to prove it.