Q. Why are men’s eyes of divers colours? A. By reason of diversity of humours. The eye hath four coverings and three humours. The first covering is called consolidative, which is the outermost, strong and fat. The second is called a horny skin or covering, of the likeness of a horn; which is a clear covering. The third, uvea, of the likeness of a black grape. The fourth is called a cobweb. The first humour is called _abungines_, from its likeness unto the white of an egg. The second _glarial_; that is, clear, like unto crystalline. The third, _vitreous_; that is, clear as glass. And the diversity of humours causeth the diversity of the eye. Q. Why are men who have but one eye good archers? and why do good archers commonly shut one eye? And why do such as behold the stars look through a trunk with one eye? A. This matter is handled in the perspective arts; and the reason is, as it doth appear in _The Book of Causes_, because that every virtue and strength united and knit together is stronger than when dispersed and scattered. Therefore all the force of seeing dispersed in two eyes, the one being shut, is gathered into the other; and so the light is fortified in him; and by consequence he doth see better and more certainly with one eye being shut, than when both are open. Q. Why do those that drink and laugh much shed most tears? A. Because that while they drink and laugh without measure, the air which is drawn in doth not pass out through the wind-pipe, and so with force is directed and sent to the eyes, and by their pores passing out, doth expel the humours of the eyes; which humour being so expelled brings tears. Q. Why do such as weep much, urine but little? A. Because the radical humidity of a tear and of urine are of one and the same nature; and therefore, where weeping doth increase, urine diminishes. And that they are of one nature is plain to the taste, because they are both salt. Q. Why do some that have clear eyes see nothing? A. By reason of the oppilation and naughtiness of the sinews with which we see; for the temples being destroyed, the strength of the light cannot be carried from the brain to the eye. Q. Why is the eye clear and smooth like glass? A. 1. Because the things which may be seen are better beaten back from a smooth thing than otherwise, that thereby the sight should strengthen. 2. Because the eye is moist above all parts of the body, and of a waterish nature; and as the water is clear and smooth, so likewise is the eye. Q. Why do men and beasts who have their eyes deep in their head see best far off? A. Because the force and power by which we see is not dispersed in them, and doth go directly to the thing which is seen. Thus, when a man doth stand in a deep ditch or well, he doth see in the day-time the stars of the firmament; because then the power of the sight and of the beams are not scattered.