I thought a little too long this time, for when I turned again to speak to my strange companion, she had left me. I tried to follow, but could not find her; and if she returned soon, it must have been by some other road. Though I looked in all directions, she was invisible to me. Now, the question will arise in your mind: In what language did I talk with this aerial servant of a French magician? I seemed to speak in my own tongue, and she seemed to respond in the same. How is that? I cannot say, unless we really used the subtle language of thought itself. You may often, on meeting with a person whose language you do not speak, feel an interchange of ideas, by the look of the eyes, by the expression of the face, by gestures. Now imagine that, intensified a hundredfold. Might it not extend to the simple questions and answers which I exchanged with the sylph? I do not say that it would, but I think it might; for, as I said before, I seemed to speak and she seemed to reply in my own language. What strange experiences one has out here! I rather dread to go back into the world, where it will be so dull for me for a long time. Can I exchange this freedom and vivid life for a long period of somnolence, afterwards to suck a bottle and learn the multiplication table and Greek and Latin verbs? I suppose I must--but not yet. Good night. LETTER XXXI A PROBLEM IN CELESTIAL MATHEMATICS BY the vividness with which you feel my presence at times, you can judge of the intensity of the life that I am living. I am no pallid spook, dripping with grave-dew. I am real, and quite as wholesome--or so it seems to me--as when I walked the earth in a more or less unhealthy body. The ghastly spectres, when they return, do not talk as I talk. Ask those who have seen and heard them. It is well that you have kept yourself comparatively free of communications “from the other world.” It would have been amazing had you been afraid of me. But there are those who would be, if they should sense my presence as you sense it. One night I knocked at the door of a friend’s chamber, half expecting a welcome. He jumped out of bed in alarm, then jumped back again, and pulled the blanket over his head. He was really afraid that it might be I! So, as I did not wish to be responsible for a case of heart failure, or for a shock of hair which, like that in the old song, “turned white in a single night,” I went quietly away. Doubtless he persuaded himself next day that there were mice in the wainscoting. Had you been afraid of me, though, I should have been ashamed of you; for you know better. Most persons do not. It is a real pleasure for me to come back and talk with you sometimes. “There are no friends like the old friends,” and the society of sylphs and spirits would never quite satisfy me if all those whom I had known and loved should turn their backs on me.