Ron Powers, in Mark Twain: A Life, introduces us to Wales McCormick, a teenage chum of young Sam Clemens, who worked as typesetter along with Sam in the print shop of Joseph P. Ament in Hannibal, Missouri. Sam, writes Powers, was awed by Wales' "genial amorality."
As an adult, Sam, now known as Mark Twain, often told the story of what happened when Alexander Campbell, the famous preacher and a founder of the Disciples of Christ, preached in Hannibal. When Campbell's followers desired a copy of his sermon, he took his manuscript to Ament's shop and there encountered Wales McCormick.
In one version of the story, Twain insisted that when Campbell stopped by Ament's shop with the sermon, he overheard McCormick exclaim, Great God! The preacher took the the boy aside and admonished him that "Great God!" was blasphemy, and that "Great Scott!" would be one example of an acceptable substitute. McCormick apparently took this to heart; while correcting the proof sheet of the sermon, he dutifully changed Campbell's own pious use of "Great God" to "Great Scott." Taken with the spirit, he amended "Father, Son & Holy Ghost" to "Father, Son, & Caesar's Ghost," and then improved even that bit of euphemism - to "Father, Son & Co."
Wales's moment of divine reckoning approached when he removed the full name "Jesus Christ" from a line in the sermon to create more space, and substituted "J. C." For some reason, this infuriated Campbell as he read the proof sheet; he strode back to the print shop and commanded McCormick: "So long as you are alive, don't you ever diminish the Savior's name again. Put it all in." McCormick took this advice to heart: the revised line came out, Jesus H. Christ.
A Twain "tall tale" or truth?