A very large plain without protuberances, is an object not less rare than beautiful; and in those who see it for the first time, it must produce an emotion of wonder. This emotion, however slight, tending to its own gratification, imposes upon the mind, and makes it judge that the plain is larger than it is in reality. Divide this plain into parts, and our wonder ceases. It is no longer considered as one great plain, but as so many different fields or inclosures. The first time one beholds the sea, it appears to be large beyond all bounds. When it becomes familiar, and raises our wonder in no degree, it appears less than it is in reality. In a storm it appears larger, being distinguishable by the rolling waves into a number of great parts. Islands scattered at considerable distances, add in appearance to its size. Each intercepted part looks extremely large, and we silently apply arithmetic to increase the appearance of the whole. Many islands scattered at hand, give a diminutive appearance to the sea, by its connection with its diminutive parts. The Lomond lake would undoubtedly look larger without its islands. Furniture increaseth in appearance the size of a small room, for the same reason that divisions increase in appearance the size of a garden. The emotion of wonder which is raised by a very large room without furniture, makes it look larger than it is in reality. If completely furnished, we view it in parts, and our wonder is not raised. A low ceiling hath a diminutive appearance, which, by an easy transition of ideas, is communicated to the length and breadth, provided they bear any sort of proportion to the height. If they be out of all proportion, the opposition seizes the mind, and raises some degree of wonder, which makes the difference appear greater than it really is. PART VI. _Of the resemblance emotions bear to their causes._ That many emotions bear a certain resemblance to their causes, is a truth that can be made clear by induction; though, so far as I know, the observation has not been made by any writer. Motion, in its different circumstances, is productive of feelings that resemble it. Sluggish motion, for example, causeth a languid unpleasant feeling; slow uniform motion, a feeling calm and pleasant; and brisk motion, a lively feeling that rouses the spirits and promotes activity. A fall of water through rocks, raises in the mind a tumultuous confused agitation, extremely similar to its cause. When force is exerted with any effort, the spectator feels a similar effort as of force exerted within his mind. A large object swells the heart. An elevated object makes the spectator stand erect. Sounds also produce emotions that resemble them. A sound in a low key, brings down the mind. Such a sound in a full tone, hath a certain solemnity, which it communicates to the emotion produced by it. A sound in a high key, chears the mind by raising it. Such a sound in a full tone, both elevates and swells the mind.