“early 18th century: originally denoting an apparatus similar to that used to ring a church bell (but without the bell, so noiseless or ‘dumb’); dumbbell (sense 2) (dating from the 1920s) is an extended use by association with dumb ‘stupid’.”
“Well, it’s a marvelous night for a moondance, With the stars up above in your eyes, A fantabulous night to make romance ‘Neath the cover of October skies. And all the leaves on the trees are falling To the sound of the breezes that blow, And I’m trying to please to the calling Of your heartstrings that play soft and low…”
“early 18th century: originally denoting an apparatus similar to that used to ring a church bell (but without the bell, so noiseless or ‘dumb’); dumbbell (sense 2) (dating from the 1920s) is an extended use by association with dumb ‘stupid’.”