Page:1888 Cicero's Tusculan Disputations.djvu/316

 them, and firm in their texture, to preserve the eyes. She has made them slippery and movable, that they might avoid what would offend them, and easily direct the sight wherever they will. The actual organ of sight, which is called the pupil, is so small that it can easily shun what ever might be hurtful to it. The eyelids, which are their coverings, are soft and smooth, that they may not injure the eyes; and are made to shut at the apprehension of any accident, or to open at pleasure; and these movements nature has ordained to be made in an instant: they are fortified with a sort of palisade of hairs, to keep off what may be noxious to them when open, and to be a fence to their repose when sleep closes them, and allows them to rest as if they were wrapped up in a case. Besides, they are commodiously hidden and defended by eminences on every side; for on the upper part the eyebrows turn aside the perspiration which falls from the head and forehead; the cheeks beneath rise a little, so as to protect them on the lower side; and the nose is placed between them as a wall of separation. The hearing is always open, for that is a sense of which we are in need even while we are sleeping; and the moment that any sound is admitted by it we are awakened even from sleep. It has a winding passage, lest anything should slip into it, as it might if it were straight and simple. Nature also hath taken the same precaution in making there a viscous humor, that if any little creatures should endeavor to creep in, they might stick in it as in bird lime. The ears (by which we mean the outward part) are made prominent, to cover and preserve the hearing, lest the sound should be dissipated and escape before the sense is affected. Their entrances are hard and horny, and their form winding, because bodies of this kind better return and increase the sound. This appears in the harp, lute, or horn; and from all tortuous and enclosed places sounds are returned stronger. The nostrils, in like manner, are ever open, because we have a continual use for them; and their entrances also are rather narrow, lest anything noxious should enter