“I don’t recall having seen that quote in prior discussions of “keystone” ... was I missing it? That is possibly the best translation I’ve seen!”
I agree.
below is the unadulterated quote I found, I will dig further. When I am certain of accuracy of quote I will make a meme of Jefferson's bust with the quote for the thread. You are right of course to want to get it exact. When I finish the meme I want to figure how to embed it in emails to my house and senate critters. I have self-stick postcards, I may print out memes to stick and mail. Q said be loud.
"This [bill] on education would [raise] the mass of the people to the high ground of moral respectability necessary to their own safety and to orderly government, and would [complete] the great object of qualifying them to secure the veritable aristoi for the trusts of government, to the exclusion of the pseudalists... I have great hope that some patriotic spirit will... call it up and make it the keystone of the arch of our government." --Thomas Jefferson to John Adams, 1813. ME 13:400