“Monsieur,” he replied, in the tones of an old conspirator, “this afternoon the professor and that other monsieur went as usual to walk in the forest.” He bent over me, pretending to be busy with the coffee-machine, and lowering his voice to a hoarse whisper. “When they returned, this book fell from the pocket of that other monsieur’s coat as he ascended the stair, and he did not notice. Later I shall return it by Glouglou, but I thought it wise that monsieur should see it for himself.”

The book was Wentworth’s Algebra—elementary principles. Painful recollections of my boyhood and the binomial theorem rose in my mind as I let the leaves turn under my fingers. “What do you make of it?” I asked.

His tone became even more confidential. “Part of it, monsieur, is in English; that is plain. I have found an English word in it that I know—the word ‘O.’ But much of the printing is also in Arabic.”

“Arabic!” I exclaimed.

“Yes, monsieur, look there.” He laid a fat forefinger on “(a + b)2 = a2 + 2ab + b2.” “That is Arabic. Old Gaston has been to Algeria, and he says that he knows Arabic as well as he does French. He looked at the book and told me it was Arabic. Truly! Truly!”

“Did he translate any of it for you?”

“No, monsieur; his eyes pained him this afternoon. He says he will read it to-morrow.”

“But you must return the book to-night.”

“That is true. Eh! It leaves the mystery deeper than ever, unless monsieur can find some clue in those parts of the book that are English.”

I shed no light upon him. The book had been Greek to me in my tender years; it was a pleasure now to leave a fellow-being under the impression that it was Arabic.