Because the crystalline lens of the eye is a moveable body, and is pushed forward, or drawn back by fine muscular fibres, according to the distances of the objects upon which we look. By these means its focus becomes adjusted.
Because, by the repeated action of winking, the eye is kept moist and clean, and the watery fluid secreted by little glands in the eyelids, and at the sides of the eye, is spread equally over the surface, instead of being allowed to accumulate. But the action of winking, or brightening the eye, is so instantaneous that it does not impede the sight.
"And the eye cannot say unto the hand, I have no need of thee; nor again the head to the feet, I have no need of you."—Corinth. xii.
976. Whence are the humours and secretions of the eye derived?
From the blood, which flows abundantly to the eyes, and is circulated in capillary vessels that are spread out upon the membranous coats of the eye-balls.
