Blast from past or hot air?

THE frustrating thing about history is it's forever being rewritten.

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This makes it hard to keep up. I’m not saying it isn’t important that we make fresh discoveries, continue questioning old assumptions, etc, etc.It’s just there’s one thing I struggle with. Namely, the tendency of historians to sound so utterly sure of themselves, as if the version of events they're delivering now, in documentaries such as this one, must henceforth be considered definitive, effectively set in stone.