“I’m afraid I didn’t explain that,” she smiled. “A double negative is—let me see—well, you say, ‘never helped nobody.’ ‘Never’ is a negative. ‘Nobody’ is another negative. It is a rule that two negatives make a positive. ‘Never helped nobody’ means that, not helping nobody, they must have helped somebody.”
“That’s pretty clear,” he said. “I never thought of it before. But it don’t mean they must have helped somebody, does it? Seems to me that ‘never helped nobody’ just naturally fails to say whether or not they helped somebody. I never thought of it before, and I’ll never say it again.”
She was pleased and surprised with the quickness and surety of his mind. As soon as he had got the clew he not only understood but corrected her error.
“You’ll find it all in the grammar,” she went on. “There’s something else I noticed in your speech. You say ‘don’t’ when you shouldn’t. ‘Don’t’ is a contraction and stands for two words. Do you know them?”
He thought a moment, then answered, “‘Do not.’”
She nodded her head, and said, “And you use ‘don’t’ when you mean ‘does not.’”
He was puzzled over this, and did not get it so quickly.
“Give me an illustration,” he asked.
“Well—” She puckered her brows and pursed up her mouth as she thought, while he looked on and decided that her expression was most adorable. “‘It don’t do to be hasty.’ Change ‘don’t’ to ‘do not,’ and it reads, ‘It do not do to be hasty,’ which is perfectly absurd.”
He turned it over in his mind and considered.