The undulating and serpentine lines which art seeks always to design in its most beautiful productions, exist in greater number at the surface of the human body than at that of any other animal. Wherever, as Hogarth observes, "for the sake of the necessary motion of the parts, with proper strength and agility, the insertions of the muscles are too hard and sudden, their swellings too bold, or the hollows between them too deep, for their outlines to be beautiful; nature softens these hardnesses, and plumps up these vacancies with a proper supply of fat, and covers the whole with the soft, smooth, springy, and, in delicate life, almost transparent skin, which, conforming itself to the external shape of all the parts beneath, expresses to the eye the idea of its contents with the utmost delicacy of beauty and grace." It is principally in the features of the face, as has often been observed, and on the surface of the torso and of the members of a beautiful woman, that these delicate, bending, varied, and contrasted lines are multiplied: by their union, they mark the outlines of different parts, as in the region of the neck, of the bosom, at the shoulders, on the surface of the abdomen, on the sides, and principally in the gradual transitions from the head to the neck, and from the loins to the inferior extremities. These lines vary under different circumstances; much enbonpoint producing round lines, and leanness or old age producing straight ones. Woman and man stand pre-eminent among animals as to this kind of beauty; and to them succeed the swifter animals, as the horse, the stag, &c. The animals, on the contrary, of which the surface presents right lines and square forms, are correspondingly deprived of beauty; as the toad, the hog, and all the animals which seem to us ugly. In all animals, also, the beauty of color, even when slightly varied, becomes extremely interesting.--In human beauty, considerable variety is produced by the different shades of the skin. Such, indeed, is the variety resulting from all this, that some degree even of intricacy is produced. The undulating lines which cross in every direction, and the tortuous paths of the eye, are the means of an agreeable complication. Hence Burke, following Hogarth, says: "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?