"A republic, if you can keep it." -- Benjamin Franklin (b. 1706-01-17*, d. 1790-04-17), when asked, after the signing of the US Constitution, which style of government had been decided upon
This was recorded in the diary of James McHenry (b. 1753-11-16, d. 1816-05-03), another delegate to the Constitutional Convention, the following day (1787-09-18): "A lady asked Dr. Franklin Well Doctor what we got a republic or a monarchy -- A republic replied the Doctor if you can keep it. The lady here alluded to was Mrs. Powel of Philadelphia."
This is usually told as having happened right outside Independence Hall, as the delegates were leaving, with the woman being anonymous, but as pointed out by Professor Buzzkill (Dr. Joseph Coohill), it more likely happened at Elizabeth Powel's house, where movers and shakers in Philadelphia were often guests at parties and salons. (But Prof. Buzzkill also points out that Mrs. Powel wrote to a relative in 1814 that she didn't remember that specific conversation with Franklin.)
[*] Recorded as 1705-01-06 because when he was born England and her colonies used the Julian calendar (with 25 March as the date the year number changed, not 1 January).
I wish everyone celebrating it a good United States Independence Day. And whether you're feeling like celebrating today or not, I hope that in this precarious time with various forces trying to preserve, usurp, or divide our republic, we do manage to keep it.