Our Daily Bleg: More Quote Authors Uncovered

Three weeks ago, I invited readers to submit quotations for which they wanted me to try to trace the origins, using The Yale Book of Quotations and more recent research by me. Dozens responded via comments or e-mails. I am responding as best I can, a couple per week.
Mark C asks:
I’d love to see a definitive attribution to this old favorite, which I’ve seen attributed to Elvis Costello, Frank Zappa, and others:

Talking/writing about music is like dancing about architecture.

The earliest occurrence of this found by The Yale Book of Quotations was the following by Elvis Costello, quoted in Musician, October 1983:

Writing about music is like dancing about architecture.

TRad writes:

“Any 20-year-old who isn’t a liberal doesn’t have a heart, and any 40-year-old who isn’t a conservative doesn’t have a brain.” I’ve seen it attributed to several persons, most often to Bismarck or Churchill.

I wrote about this in my column in the Yale Alumni Magazine:

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 to 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?