I think it is sense.

I have no doubt that every year millions and millions of bushels of turnips are spoiled in this township alone by being pulled in a half-ripe condition, when, if they had sent a boy up to shake the tree--" "Shake your grandmother! Turnips don't grow on trees!" "Oh, they don't, don't they?
Well, who said they did?
The language was intended to be figurative, wholly figurative.

Anybody that knows anything will know that I meant that the boy should shake the vine." Then this old person got up and tore his paper all into small shreds, and stamped on them, and broke several things with his cane, and said I did not know as much as a cow; and then went out and banged the door after him, and, in short, acted in such a way that I fancied he was displeased about something.

But not knowing what the trouble was, I could not be any help to him.
Pretty soon after this a long, cadaverous creature, with lanky locks hanging down to his shoulders, and a week's stubble bristling from the hills and valleys of his face, darted within the door, and halted, motionless, with finger on lip, and head and body bent in listening attitude.

No sound was heard.
Still he listened.