I do not tell all that we learnt as we searched the pages of this book, such as the maps of the reverse surface of the interior, and stranger things on which I am entirely silent, because we did not actually see them, and they are too incredible to be lightly added to a narrative which must appear fictitious, in any case, to the obtuse and unimaginative. It is not every one who can realise that the human mind has no real power of invention, nor that it is impossible to add to that which is infinite. We went down in vision for five hundred miles by one continuing spiral, seeing glimpses of inexplicable things on many levels, until we came to a place in which were two colonies of the older Dwellers, each attempting to postpone the weariness of years by activities of the mind, and who were known (by the nearest synonyms in our language) as the Seekers of Wisdom, and the Seekers of Science. I write _science_ rather than _knowledge_ because the impression I received was similar to that which has degraded the use of the former word, so that its implication is of the assertion of speculative theories with a dogmatism equal to that of the theologians whom it despises, and with a lack of imagination and spiritual perception which insures that scientific hand-books of one decade become the derision of the next. We ascertained and memorised very carefully the passages by which the descending spiral could be reached, and the ways which must be taken when we left it. We could not discover whether they were the channels of crowded traffic, or lonely as the dark tunnels which we had already penetrated, but we had gained much in having learnt the way by which we must go, and our next task was to find an exit from the library. We should have pursued this purpose, and might have continued the adventure together, and completed it successfully, had we not been drawn aside to observe a movement among the books at the farther side of the library. It was foolish in itself, and disastrous in its consequence, but the sight which drew us was sufficiently curious to be some excuse for our error. CHAPTER XIII SEPARATION In a large room, or recess, at the side of the library, there was a tank completely covering its floor, and filled, to a depth of about three feet, with a watery liquid, slightly tinged with carmine. An arrangement of gently-sloping boards had enabled the books of several tiers of shelves to make their way to this tank, into which they plunged, and floated with an appearance of satisfaction, working their hands in such a way that they turned over continually, in a very comical manner. It required no very great penetration to see that this was a place of refreshment, or nourishment, which was needed to maintain their vitality, but it was one which they could not reach without an intervening danger.