It’s day #3 of The Great Quotists – Mr. Samuel Langhorne Clemens if you please.
The words ‘mark twain’ are what the steamboat pilots of the 1800s would call out when the measurement of the water on the river was at least 2 fathoms.  It meant that the water was deep enough for the boats to travel safely.  Samuel Clemens was a steamboat pilot along the Mississippi River and took those words as his pen name in 1863.  It also is the case that an earlier Mississippi steamboat captain, one Captain Sellers, used that as his pen name before Clemens did.  Clemens supposedly chose the name in honor of that first writer and as a connection to his roots on the river.



Drawing by Marty Coleman of The Napkin Dad Daily 

Quote by Mark Twain – NOTE:  While this quote has long been attributed to Twain, there is some reason to doubt whether he actually said it.  Record going back to early in his life attribute the quote to Ebenezer Rockwood Hoar.