John Adams Said it First

I’m back to inviting readers to submit quotations whose origins they want me to try to trace, using my book, The Yale Book of Quotations, and my more recent researches.
Daniel Greenwald asked:

“If a person is not a liberal when he is twenty, he has no heart; if he is not a conservative when he is forty, he has no head.’ OR
‘If my son is not a liberal when he is twenty, I will disown him; if he is not a conservative when he is forty, I will disown him then.’
And other variants, I am sure.”

Photo: cliff1066™

One of the pleasures of compiling the Yale Book of Quotations was tracing and cross-referencing different versions and precursors of famous quotes. This one is usually credited to Georges Clemenceau, but W. Gurney Benham‘s Book of Quotations cites French premier and historian Francois Guizot (1787-1874), translating his statement as “Not to be a republican at 20 is proof of want of heart; to be one at 30 is proof of want of head.” Benham asserts that “Clemenceau adopted this saying, substituting ‘socialiste’ for ‘republicain. ‘”
But I was delighted to find that John Adams had expressed a similar idea well before Guizot entered adulthood. Thomas Jefferson preserved this quip, writing in a 1799 journal that Adams had said: “A boy of 15 who is not a democrat is good for nothing, and he is no better who is a democrat at 20.”
Do any readers have any other quotations whose origins they would like me to attempt to trace?