Quotes Uncovered: If at 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 research.
Les Hankes asked:

I have tried to find the origin of the following without success: “For all sad words of tongue and pen, The saddest are these, ‘It might have been.'” Thanks if you find something.

According to that estimable reference work, The Yale Book of Quotations, this comes from John Greenleaf Whittier‘s poem “Maud Muller” (1854).
Canada Kid asked:

“If at first you don’t succeed, try, try again.” or any variation of that. I read it in a fictional book about the prairie and midwest, in the 1800s. I thought something like that was older, maybe Shakespearian time.

The YBQ cites this as follows:

Thomas H. Palmer, Quoted in The Village Reader (1840). The identical words, except with “try, try, try again,” appear in a poem titled “Perseverance; or, Try Again,” printed in Common School Assistant, Aug. 1838. No author is identified.

W. C. Fields is attributed the variant, “If at first you don’t succeed, try, try again. Then quit. There’s no use being a damn fool about it.”
Do any readers have any other quotations whose origins they would like me to attempt to trace?