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It only took us a century and a half, but we may have finally learned the real source of Samuel Clemens' ubiquitously recognizable nom de plume: he stole it from a humor journal so lame that he quickly invented a cooler story to pass off as true. But he wouldn't have gotten away with such a trick today.

The theory is according to a find by a Texas book dealer and scholar, who managed to stumble upon what seems to be the first recorded appearance of the name "Mark Twain"—in a humor journal called Vanity Fair (no, not the contemporary magazine) two years before Samuel Clemens adopted it. Thankfully, Austin's Kevin Mac Donnell was sharp enough to recognize the significance of his find, though he was really only poking around Google Books and modestly told the Los Angeles Review of Books that anyone could have done the same:

“I wasn’t looking for what I found. I stumbled across it,” Mac Donnell said in a phone interview. With a flair for folksy humor that made Twain famous, he also added that “you could train a cat to do what I did. You could train a garden slug to do what I did, but the cat would be quicker.”

Scholars have never been clear on the source of Twain's pseudonym, but stories emerged during his lifetime. One famously suggested "Mark twain!" was the writer's trademark cry in a Virginia City saloon he frequented, meaning "Mark two more drinks." Twain himself claimed an altogether different source for his pseudonym: he said the name had been used by Isaiah Sellers, a riverboat captain who died in 1863, and "as he could no longer need that signature, I laid violent hands upon it without asking permission of the proprietor's remains."