Quotes Uncovered: From Soldiers to Farmers to Poets

A while back, 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. Hundreds of people have responded via comments or e-mails. I am responding as best I can, a few per week.
Michael asked:

It’s often attributed to Samuel Clemens, but can you verify that he said “The coldest winter I ever saw was the summer I spent in San Francisco”?

The Yale Book of Quotations, which attempts to trace all famous quotations to their earliest sources, has the following:

“Anywhere is better than Paris. Paris the cold, Paris the drizzly, Paris the rainy, Paris the damnable. More than a hundred years ago somebody asked Quin, ‘Did you ever see such a winter in all your life before?’ ‘Yes,’ said he, ‘Last summer.’ I judge he spent his summer in Paris.”
Mark Twain, Letter to Lucius Fairchild, April 28, 1880. This letter is the closest source that has been found for the saying, frequently credited to Twain, that “The coldest winter I ever spent was a summer in San Francisco.” The Quin referred to was an 18th-century actor and wit.

Patrick asked:

I have searched for this but cant find it; the quote is something like “I am a soldier so my children can be farmers so their children can be poets,” or something along those lines.

Again, The Yale Book of Quotations has the answer:

“I must study Politicks and War that my sons may have liberty to study Mathematicks and Philosophy. My sons ought to study mathematicks and philosophy, geography, natural history, naval architecture, navigation, commerce, and agriculture, in order to give their children a right to study painting, poetry, musick, architecture, statuary, tapestry, and porcelaine.” John Adams, Letter to Abigail Adams, May 12, 1780.

Do any readers have any other quotations whose origins they would like me to attempt to trace?