As we have, in the former six Views, been gradually mounting above the mists and illusions of our everyday thoughts, and can look through our Window with, I hope, a clearer vision, I shall venture in this present View to carry the subject of the _Future_ still further, and show that, just as we have now before us and can read the papyri which were written 5000 years ago, so it is possible to conceive that books, written and being written and printed 5000 years hence, are _at present_ in existence, and that it is even possible the human race has actually already read them; whether we shall be able to see them and read them in our own lifetime may be open to question; that may again depend upon the development of special cross-circuiting of brain filaments. Meanwhile, in order to carry our present View to the utmost limit of our conception, in a manner somewhat similar to what we did for Space, I will again ask you to join me in a thought-flight towards the appreciation of this second great Mystery. With this object in view we will first consider the human senses of sight and hearing, commencing with sound, or the vibrations which affect the tympanum of the human ear. Sound travels in air at about 1130 feet per second, and if the vibrating body, giving out the sound, oscillates sixteen times in one second, it follows that, spreading over this 1130 feet, there will be sixteen waves, giving a length of about 70 feet to each wave. This is the lowest sound that the human ear can appreciate as a musical note, and is, what may be called, the fourth Octave above one vibration in one second. When the number of vibrations in a second sinks below sixteen, the ear no longer appreciates them as a musical sound, but is able to hear them as separate vibrations or beats. The easiest way of illustrating this is by means of a revolving disc, with sixteen holes pierced at regular intervals round the edge, and a jet of high-pressure air, which is forced through each of the holes successively as they revolve. When the disc does not quite complete one revolution in a second, only fifteen puffs come to the ear in a second of time, and they are heard as puffs; but when the rate reaches one revolution in a second, the sound, as if by magic, changes into the lowest musical sound. The same result may be obtained in a more pronounced form by means of explosions or pistol shots; when these are slow and heard separately, they are painful and almost unbearable to the ear, but, as soon as their rapidity, namely, at sixteen per second, gets beyond the power of the ear to differentiate between the explosions, the impression, as if by magic, changes into a continuous or musical sound, like a thirty-foot pipe note of an organ.