jts wrote:...But nonetheless, the Romans had no concept of radio waves, and that affected the way ordinary Romans lived, and the way elite Romans thought about the world. ...
But the Romans didn't lack knowledge about radio waves because they spoke Latin, they were ignorant about radio waves because they lived ~2000 years ago.
Nobody knew about radio waves, and if the Egyptians of the time had discovered the radio wave, it's pretty certain that Latin would soon have had a convenient way of expressing it.
Or maybe you're suggesting that we can deduce, from the lack of a simple expression in Latin for "radio wave", that the Romans had no knowledge of it. Well, maybe, but it seems like there ought to be
lots of better ways to come to that conclusion; we know the generalization of that ("people who speak languages lacking words for X lack concept X") is not true. As robinz said, in the case of schadenfreude, the fact that there's no short native English word for it by no means implies that the concept of pleasure at one's enemy's misfortune is absent from the mind of the English speaker. So, I think it's hard to establish anything via a "no word for X" argument that couldn't be established better and more convincingly via other means.
Besides, if you read many of the language log posts in the archive I linked, you'll notice that usually the party claiming "no word for X" is just simply wrong.
