I read a lot growing up and my elementary school spent an inexplicable amount of time teaching Jewish history and so on, but I wouldn't have recognized that line until a year or so ago. (I have no idea why my elementary school was like that. There were fewer than 100 students, most of them were black, and when I looked the school up a few years ago, it looked to be nominally affiliated with some mainline Protestant church.)

I only know of it through LW, so it could be that Harry had a few Jewish tutors and overheard them talking amongst themselves. I would expect someone who wants to conquer^Woptimize the world to read up on the successful cultures of the world and their social technology, but I can't see Harry doing that. Maybe he's wiser than I give him credit for. Then again, I still haven't done that specific bit of reading. Are there any good books on it?