Well, the original shop was opened by a retired printer by the name of Gruby. Mr. Gruby, being left-handed himself, thought of the idea to try to promote a few products for left-handers.
Within a year of his father's death, he quit school and became an apprentice printer, and when his brother Orion bought the Hannibal Journal in 1851, Twain went to work for him as a printer and editorial assistant.
So teenage Ben runs away, spends a year in London making friends with scientific smartypantses, and returns to Philadelphia a printer by trade, but a scientist in his heart.
Before the end of the eighteenth century, the skilled workmen—printers, shoemakers, tailors, and carpenters—had, as we have seen, formed local unions in the large cities.