"Were I to tell you," he said at last, "by what mystical authority and influence you were compelled to come here, by what a marvellously linked chain of circumstances you became known to me long before I saw you; how I was made aware that you were the only woman living to whose companionship I could trust my sister at a time when the society of one of her own sex became absolutely necessary to her; how you were marked out to me as a small point of light by which possibly I might steer my course clear of the darkness which threatened me--I say, were I to tell you all this, you would no longer doubt the urgent need of your presence here. It is, however, enough to tell you that you have fulfilled all that was expected of you, even beyond my best hopes; and in return for your services, the worth of which you cannot realize, whatever guidance I can give you in the future for your physical and spiritual life, is yours. I have done something for you, but not much--I will do more. Only, in communicating with me, I ask you to honour me with your full confidence in all matters pertaining to yourself and your surroundings--then I shall not be liable to errors of judgment in the opinions I form or the advice I give." "I promise most readily," I replied gladly, for it seemed to me that I was rich in possessing as a friend and counsellor such a man as this student of the loftiest sciences. "And now one thing more," he resumed, opening a drawer in the table near which he sat. "Here is a pencil for you to write your letters to me with. It will last about ten years, and at the expiration of that time you can have another. Write with it on any paper, and the marks will be like those of an ordinary drawing-pencil; but as fast as they are written they disappear. Trouble not about this circumstance--write all you have to say, and when you have finished your letter your closely covered pages shall seem blank. Therefore, were the eye of a stranger to look at them, nothing could be learned therefrom. But when they reach me, I can make the writing appear and stand out on these apparently unsullied pages as distinctly as though your words had been printed. My letters to you will also, when you receive them, appear blank; but you will only have to press them for about ten minutes in this"--and he handed me what looked like an ordinary blotting-book--"and they will be perfectly legible. Cellini has these little writing implements; he uses them whenever the distances are too great for us to amuse ourselves with the sagacity of Leo--in fact the journeys of that faithful animal have principally been to keep him in training." "But," I said, as I took the pencil and book from his hand, "why do you not make these convenient writing materials public property? They would be so useful."