Know the ropes
Q From John Lanahan, Berlin: Could you please explain the expression, To teach someone the ropes? Is this a naval or circus term at all?
A It pairs up with know the ropes, which is a lot more common. Learn the ropes is also often found. All are from seafaring.
You only have to look at pictures of old-time sailing ships to get the point. A vast amount of cordage supported the masts as well as the running rigging that controlled the sails and yards. Every rope or line had a purpose and every one was essential to control the vessel; loosen or pull the wrong one at a critical moment and all hell might break loose. So it was vital that the crew knew the ship’s ropes: to learn them was the basic skill of any sailor.
The expression is first recorded in Richard Dana’s Two Years Before the Mast in 1840: “The captain, who had been on the coast before, and ‘knew the ropes,’ took the steering-oar, and we went off in the same way as the other boat.” It’s almost certainly a lot older as a seafarer’s term, because Dana is already using it in the current figurative sense of knowing how to do something or being fully knowledgeable or experienced.