Juanito, or rather Placido, who was prompting him, was unconsciously adopting Chinese tactics:  not to admit the most inoffensive foreigner in order not to be invaded.

“Then where are we?” asked the professor, somewhat disconcerted, and looking uneasily at the refractory student.  “Does the substance behind affect, or does it not affect, the surface?”

To this precise and categorical question, a kind of ultimatum, Juanito did not know what to reply and his coat offered no suggestions.  In vain he made signs to Placido, but Placido himself was in doubt.  Juanito then took advantage of a moment in which the professor was staring at a student who was cautiously and secretly taking off the shoes that hurt his feet, to step heavily on Placido’s toes and whisper, “Tell me, hurry up, tell me!”

“I distinguish—­Get out!  What an ass you are!” yelled Placido unreservedly, as he stared with angry eyes and rubbed his hand over his patent-leather shoe.

The professor heard the cry, stared at the pair, and guessed what had happened.

“Listen, you meddler,” he addressed Placido, “I wasn’t questioning you, but since you think you can save others, let’s see if you can save yourself, salva te ipsum, and decide this question.”

Juanito sat down in content, and as a mark of gratitude stuck out his tongue at his prompter, who had arisen blushing with shame and muttering incoherent excuses.

For a moment Padre Millon regarded him as one gloating over a favorite dish.  What a good thing it would be to humiliate and hold up to ridicule that dudish boy, always smartly dressed, with head erect and serene look!  It would be a deed of charity, so the charitable professor applied himself to it with all his heart, slowly repeating the question.

“The book says that the metallic mirrors are made of brass and an alloy of different metals—­is that true or is it not true?”

“So the book says, Padre.”

“Liber dixit, ergo ita est.  Don’t pretend that you know more than the book does.  It then adds that the glass mirrors are made of a sheet of glass whose two surfaces are well polished, one of them having applied to it an amalgam of tin, nota bene, an amalgam of tin!  Is that true?”

“If the book says so, Padre.”

“Is tin a metal?”

“It seems so, Padre.  The book says so.”

“It is, it is, and the word amalgam means that it is compounded with mercury, which is also a metal. Ergo, a glass mirror is a metallic mirror; ergo, the terms of the distinction are confused; ergo, the classification is imperfect—­how do you explain that, meddler?”

He emphasized the ergos and the familiar “you’s” with indescribable relish, at the same time winking, as though to say, “You’re done for.”

“It means that, it means that—­” stammered Placido.

“It means that you haven’t learned the lesson, you petty meddler, you don’t understand it yourself, and yet you prompt your neighbor!”