There are many popular answers. I have found this quotation being attributed to Hemingway, Cicero, Voltaire, Mark Twain, and Blaise Pascal. Until recently, I felt that this was Twain's work. But now I am fairly convinced that this is Blaise Pascal's work.


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I’ve always believed this was Mark Twain’s work as well. According to brainyquote.com it is Blaise’s work.
I have made this letter longer than usual, only because I have not had the time to make it shorter.
Actually, I’ve been told that President Lincoln wrote that.
This has long been attributed to Blaise Pascal.
Twain was not the only sardonic wit in the last few centuries.
It is really surprising. But Mark Twain and Blaise Pascal both were exceptional contributor..
i have to disagree. my understanding is that it was george bernard shaw who once wrote, “Sorry for the letter, i didn’t have time to write a postcard.”
It was the Canadian Poet T.S. Eliot
Oh, my unknown friends, it goes further back than that. Voltaire, Virgil and others in my research have all laid claim to quote. My favorite version, however, was from an unknown speaker at a celebration in 2002 advising on what he was about to do: “Be brief, brother, be brief.”
When Jean-Paul Sartre did his speech in the Sorbonne court in may 1968, someone put a placard before him: “Sartre, sois bref!”. Sartre, be brief!”
I saw it!
Apparently T.S. Elliot has also been cited!