“There is nothing incredible about it,” I said. “It is all very reasonable. Moreover, there is no such thing as a colour at all, for what we call by that name refers only to a certain sensation which is produced in our brains by means of certain vibrations transmitted through the retina and the optic nerve. If you look at any coloured thing in the dark you will find it to be without any colour at all. The sensations we receive are only due to certain vibrations of something unknown.” “What is a vibration?” asked Adalga. “Vibration,” I said, “is nothing but a certain kind of motion, and as motion _per se_ does not exist, vibration is nothing, while that unknown thing which moves must be everything. But the existence of that unknown thing is not admitted by science, and consequently science knows nothing of everything, and of everything nothing, just as you like; and you can make nothing out of everything, and everything out of nothing, at your own pleasure.” The princess was delighted to hear that she could now make everything out of nothing, although for the beginning it could be done only theoretically, and her repugnance to philosophical hair-splittings faded away. She continued her lessons with great diligence, and very soon I had the pleasure of seeing that she believed nothing and denied everything. A few weeks more, and I was highly gratified to find that she could no longer tell a mock-turtle from a tommy cat without entering into a long series of arguments for the purpose of proving which was which. Unfortunately, in proportion as she lost her power of perceiving the reality, while improving in the practice of logic, her own light grew more and more dim, her luminosity less, and the green colour in her sphere darker; but I considered this as a matter of only secondary importance; for it is said that beauty is a perishable thing, while wisdom remains. Sometimes she was inclined to worry about the fading of her charms, but I reasoned her out of it, saying: “If everything is nothing, then, as a matter of course, beauty also is nothing, and it is not worth the while to worry about the loss of nothing.” “But,” objected Adalga, “if beauty is nothing and nothing is everything, beauty is everything, and we must do all we can to preserve it.” “Beauty,” I replied, “among our people is the outcome of fashion. If it were to become fashionable in our world to wear goitrès and hunchbacks, everybody would find it beautiful and adopt it at once; and even if he did not find it beautiful, he would pretend to find it so. Thus it often happens that everybody wears a most ridiculous article of dress, not because he thinks it beautiful, but because he thinks that others do so. In this way the people act foolish, and silently laugh at each other for being such fools.” “This I should think to be very immoral,” objected Adalga.