I can't brain today, so feel free to share what this obvious third thing is supposed to be.
There are people alive today who have never held a chisel, never even seen a ramp used in construction, never handled any animals and never lifted any rocks. Why would they have any idea of how easy or hard something is?
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Re: "pyramids were built by slaves."
Current understanding is that they were built by free workers and loyal supporters of whatever regime the pyramid was made for.