[GeorgeTirebiter]

That's funny. Of course, I was referring to Asimov's Elevator Effect, which is that if aliens visited NYC with some probe in 1800 and then in 1950, they would be astonished at all the very tall buildings, and would have to assume people were now living in these tall towers for reasons TBD. They would not know that elevators had been invented, and hence, the buildings would only be occupied 8 hours per day or so; and nobody would live in them. Elevators allowed this major unexpected result. There is more, I couldn't find the actual essay.