Page:The wonders of optics (1869).djvu/28

 strike us more than any other portion of the countenance. They are, in fact, a shadow in the picture, bringing its colour and drawing into strong relief. The eyelashes also contribute their effect; when they are long and thick, they overshadow the eye, making its glance appear softer and more beautiful. The ape is the only other animal besides man that possesses two eyelashes, the rest having them only on the upper eyelid. Even in man they are more abundant in the upper eyelid than in the lower. The eyebrows have but two movements, upward and downward, governed by the muscles of the forehead. In the action of frowning we not only lower them, but move them slightly towards each other. The eyelids serve to protect the eyeball, and keep the cornea from becoming dry. The upper eyelid has the power of raising and lowering itself, the lower one being almost destitute of movement. Although the motion of the eyelids is an effort of will, there are times when it is impossible to keep them open, as for instance when we are overpowered by sleep, or when the eyes are suddenly subjected to the effects of strong light. The eyelid is a most admirable arrangement for the protection of the eye, and it is almost impossible to admire this provision of nature too much, even when we confine ourselves to an outward examination of it. It is not merely the outward mechanism and motion of the eyelids, nor the colour of the eyes, that constitutes their beauty; we have already said that the leading characteristic of the eye was expression. It is this expression which causes the eye to appear to speak, to fire up suddenly, to sparkle with flashes of light, to languish or conceal itself underneath its lashes, to raise itself with inspiration, or to pierce the abyss of thought, just according to the particular sentiment governing the mind at the moment. Hence it is expression that constitutes the true beauty of the eye: every one knows