The next property constantly observable in such objects is _smoothness_;[24] a quality so essential to beauty, that I do not now recollect anything beautiful that is not smooth. In trees and flowers, smooth leaves are beautiful; smooth slopes of earth in gardens; smooth streams in the landscape; smooth coats of birds and beasts in animal beauties; in fine women, smooth skins; and in several sorts of ornamental furniture, smooth and polished surfaces. A very considerable part of the effect of beauty is owing to this quality; indeed the most considerable. For, take any beautiful object, and give it a broken, and rugged surface; and, however well formed it may be in other respects, it pleases no longer. Whereas, let it want ever so many of the other constituents, if it wants not this, it becomes more pleasing than almost all the others without it. This seems to me so evident, that I am a good deal surprised that none who have handled the subject have made any mention of the quality of smoothness in the enumeration of those that go to the forming of beauty. For, indeed, any ruggedness, any sudden, projection, any sharp angle, is in the highest degree contrary to that idea. SECTION XV. GRADUAL VARIATION. But as perfectly beautiful bodies are not composed of angular parts, so their parts never continue long in the same right line.[25] They vary their direction every moment, and they change under the eye by a deviation continually carrying on, but for whose beginning or end you will find it difficult to ascertain a point. The view of a beautiful bird will illustrate this observation. Here we see the head increasing insensibly to the middle, from whence it lessens gradually until it mixes with the neck; the neck loses itself in a larger swell, which continues to the middle of the body, when the whole decreases again to the tail; the tail takes a new direction, but it soon varies its new course, it blends again with the other parts, and the line is perpetually changing, above, below, upon every side. In this description I have before me the idea of a dove; it agrees very well with most of the conditions of beauty. It is smooth and downy; its parts are (to use that expression) melted into one another; you are presented with no sudden protuberance through the whole, and yet the whole is continually changing. Observe that part of a beautiful woman where she is perhaps the most beautiful, about the neck and breasts; the smoothness, the softness, the easy and insensible swell; the variety of the surface, which is never for the smallest space the same; the deceitful maze through which the unsteady eye slides giddily, without knowing where to fix, or whither it is carried. Is not this a demonstration of that change of surface, continual, and yet hardly perceptible at any point, which forms one of the great constituents of beauty? It gives me no small pleasure to find that I can strengthen my theory in this point by the opinion of the very ingenious Mr.