“I saw one made, only yesterday,” the Earl replied. “Muriel, my child, were you not making one, to amuse those children you had to tea?” “Yes, I know that Puzzle,” said Lady Muriel. “The Ring has only _one_ surface, and only _one_ edge. It’s very mysterious!” “The _bag_ is just like that, isn’t it?” I suggested. “Is not the _outer_ surface of one side of it continuous with the _inner_ surface of the other side?” “So it is!” she exclaimed. “Only it _isn’t_ a bag, just yet. How shall we fill up this opening, Mein Herr?” “Thus!” said the old man impressively, taking the bag from her, and rising to his feet in the excitement of the explanation. “The edge of the opening consists of _four_ handkerchief-edges, and you can trace it continuously, round and round the opening: down the right edge of _one_ handkerchief, up the left edge of the _other_, and then down the left edge of the _one_, and up the right edge of the _other_!” “So you can!” Lady Muriel murmured thoughtfully, leaning her head on her hand, and earnestly watching the old man. “And that _proves_ it to be only _one_ opening!” [Illustration: FORTUNATUS’ PURSE] She looked so strangely like a child, puzzling over a difficult lesson, and Mein Herr had become, for the moment, so strangely like the old Professor, that I felt utterly bewildered: the ‘eerie’ feeling was on me in its full force, and I felt almost _impelled_ to say “Do you understand it, Sylvie?” However I checked myself by a great effort, and let the dream (if indeed it _was_ a dream) go on to its end. “Now, this _third_ handkerchief,” Mein Herr proceeded, “has _also_ four edges, which you can trace continuously round and round: all you need do is to join its four edges to the four edges of the opening. The Purse is then complete, and its outer surface——” “_I_ see!” Lady Muriel eagerly interrupted. “Its _outer_ surface will be continuous with its _inner_ surface! But it will take time. I’ll sew it up after tea.” She laid aside the bag and resumed her cup of tea. “But why do you call it Fortunatus’s Purse, Mein Herr?” The dear old man beamed upon her, with a jolly smile, looking more exactly like the Professor than ever. “Don’t you see, my child—I should say Miladi? Whatever is _inside_ that Purse, is _outside_ it; and whatever is _outside_ it, is _inside_ it. So you have all the wealth of the world in that leetle Purse!” His pupil clapped her hands, in unrestrained delight. “I’ll certainly sew the third handkerchief in—_some_ time,” she said: “but I wo’n’t take up your time by trying it now. Tell us some more wonderful things, please!” And her face and her voice so _exactly_ recalled Sylvie, that I could not help glancing round, half-expecting to see _Bruno_ also!