it acts like a coarse sieve” (_Vermischte Schriften_, vol. i. p. 398). I have long really held the opinion that the amount of noise which any one can bear undisturbed stands in inverse proportion to his mental capacity, and therefore may be regarded as a pretty fair measure of it. Therefore, if I hear the dogs barking for hours together in the court of a house without being stopped, I know what to think of the intellectual capacity of the inhabitants. The man who habitually slams the door of a room, instead of shutting it with his hand, or allows this to go on in his house, is not only ill-bred, but is also a coarse and dull-minded fellow. That in English “sensible” also means gifted with understanding is based upon accurate and fine observation. We shall only become quite civilised when the ears are no longer unprotected, and when it shall no longer be the right of everybody to sever the consciousness of each thinking being, in its course of a thousand steps, with whistling, howling, bellowing, hammering, whip-cracking, barking, &c. &c. The Sybarites banished all noisy trades without the town; the honourable sect of the Shakers in North America permit no unnecessary noise in their villages, and the Moravians have a similar rule. Something more is said upon this subject in the thirtieth chapter of the second volume of the “Parerga.” The effect of music upon the mind, so penetrating, so direct, so unfailing, may be explained from the _passive_ nature of hearing which has been discussed; also the after effect which sometimes follows it, and which consists in a specially elevated frame of mind. The vibrations of the tones following in rationally combined numerical relations set the fibre of the brain itself in similar vibration. On the other hand, the _active_ nature of sight, opposed as it is to the passive nature of hearing, makes it intelligible why there can be nothing analogous to music for the eye, and the piano of colours was an absurd mistake. Further, it is just on account of the active nature of the sense of sight that it is remarkably acute in the case of beasts that hunt, _i.e._, beasts of prey, while conversely the _passive_ sense of hearing is specially acute in those beasts that are hunted, that flee, and are timid, so that it may give them timely warning of the pursuer that is rushing or creeping upon them. Just as we have recognised in sight the sense of the understanding, and in hearing the sense of the reason, so we might call smell the sense of the memory, because it recalls to us more directly than any other the specific impression of an event or a scene even from the most distant past. Chapter IV. On Knowledge _A Priori_.