"Selling coals to Newcastle"
Meaning something that is entirely unnecessary, historically Newcastle being rich in coal.
However, Timothy Dexter, Author of A Pickle for the Knowing Ones or Plain Truth in a Homespun Dress(which contained some 8000 words and not a mark of punctuation in it. When it was ridiculed, he published another edition with the addition of a page bearing thirteen lines of random punctuation marks and the request that readers, " peper and solt it as they plese.")American Entrepreneur, and Lackwit Extraordinaire, defied this idiom when, using his newly valuable fortune in continental currency and relying on the advice of jealous friends, he bought a large amount of coal and sent it to Newcastle. Fantastically luckily, the shipments arrived in the middle of a Newcastle coal miners' strike.
Especially considering his almost nonexistent education, his business luck was incredible. Those same "friends" told him that there was a shortage of warming pans and mittens in the West Indies. The warming pans were then marketed by a resourceful Captain as molasses ladles and Dexter made a surprising profit. The mittens were sent to Siberia, also raking in unexpected profit. Other random items he exported are stray cats and whalebone.
So, what's the moral of the story? I think there are two:
#1. God really does use the foolish and the weak.Once again, on the advice of his friends, (Does this guy ever learn? But ignorance seems to be working for him.) he sent a large shipment of Bibles to the East Indies, where they were sold and distributed.
#2. You can be successful without intelligence, but people will still laugh at you. Despite his success, Dexter was widely and deservedly ridiculed for his ignorance. (Ahem, see above example about his book, A Pickle for the Knowing Ones.)