Recently, I attended a concert performance featuring a woman playing a pipe organ. Several small handles were on the cabinet on either side of the music holder. Like knobs they were. She would push one in and pull another out for one song, then push and pull to get different sounds from the organ for another. She was quite well trained and all four of her extremities were doing different things at the same time.
Once she pulled out every knob in sight. I leaned to my friend, the department head of the Fine Arts Department, mind you, and said, “I guess that’s pulling out all the stops!” She replied, “Very good!” The next day some Internet research led me to this entry from the Cambridge Idioms Dictionary:
pull out all the stops
to do everything you can to make something successful
Usage notes: The stops are handles on an organ (= a large instrument used in churches), which you pull out when you want to play as loudly as possible.
How about that? I was right! Sure enough, the sound from the organ was very loud and majestic. Having heard this “saying” all my life and knowing it meant something to the effect of “holding nothing back” (which is itself likely an idiom) or “Giving it your all,” I had no idea it referred to the knobs on a pipe organ. Who knew? As I said, you learn something new every day.