He went to the window and leant out, as though to discover the exact direction followed by the ray of light. Then he came and lay on the sofa again, saying: "It's your turn now. Count away!" The fellow seemed so positive that I did as he told me. Besides, I could not help confessing that there was something rather curious about the ordered frequency of those gleams on the front of the house opposite, those appearances and disappearances, turn and turn about, like so many flash signals. They obviously came from a house on our side of the street, for the sun was entering my windows slantwise. It was as though some one were alternately opening and shutting a casement, or, more likely, amusing himself by making sunlight flashes with a pocket-mirror. "It's a child having a game!" I cried, after a moment or two, feeling a little irritated by the trivial occupation that had been thrust upon me. "Never mind, go on!" And I counted away.... And I put down rows of figures.... And the sun continued to play in front of me, with mathematical precision. "Well?" said Lupin, after a longer pause than usual. "Why, it seems finished.... There has been nothing for some minutes...." We waited and, as no more light flashed through space, I said, jestingly: "My idea is that we have been wasting our time. A few figures on paper: a poor result!" Lupin, without stirring from his sofa, rejoined: "Oblige me, old chap, by putting in the place of each of those numbers the corresponding letter of the alphabet. Count A as 1, B as 2 and so on. Do you follow me?" "But it's idiotic!" "Absolutely idiotic, but we do such a lot of idiotic things in this life.... One more or less, you know!..." I sat down to this silly work and wrote out the first letters: "_Take no...._" I broke off in surprise: "Words!" I exclaimed. "Two English words meaning...." "Go on, old chap." And I went on and the next letters formed two more words, which I separated as they appeared. And, to my great amazement, a complete English sentence lay before my eyes. "Done?" asked Lupin, after a time. "Done!... By the way, there are mistakes in the spelling...." "Never mind those and read it out, please.... Read slowly." Thereupon I read out the following unfinished communication, which I will set down as it appeared on the paper in front of me: "_Take no unnecessery risks. Above all, avoid atacks, approach ennemy with great prudance and...._" I began to laugh: "And there you are! _Fiat lux!_ We're simply dazed with light! But, after all, Lupin, confess that this advice, dribbled out by a kitchen-maid, doesn't help you much!" Lupin rose, without breaking his contemptuous silence, and took the sheet of paper. I remembered soon after that, at this moment, I happened to look at the clock. It was eighteen minutes past five.