CHAP. V. Of the Eyes.
THe Eyes are the instruments of the faculty of seeing,* 1.1 brought thither by the visive spi∣rit of the optick nerves, as in an Aquae-duct. They are of a soft substance, of a large quan∣tity, being bigger, or lesser, according to the bigness of the body. They are seated in the head, that they might over-took the rest of the body, to perceive and shun such things as might endanger, or endamage the body; for the action of the eyes is most quick,* 1.2 as that which is performed in a moment, which is granted to none of the other senses. Wherefore this is the most excellent sense of them all. For by this, we behold the fabrick and beauty of the Heavens, and Earth, distinguish the infinite varieties of colours, we perceive and know the magnitude, figure, number, proportion site, motion, and rest, of all bodies. The eyes have a pyramidal figure whose basis is without, but the Cone or point within at the Optick nerves. Nature would have them contained in a hollow circle,* 1.3 that so by the profundity and solidity of the place they might be free from the incursions of bruising and hurtful things.
They are composed of six muscles, five coats, three humors, and a most bright spirit,* 1.4 (of which there is a perpetual afflux from the brain) two nerves, a double vein, and one artery, besides much fat; and lastly, a Glandule seated at the greater angle thereof,* 1.5 upon that large hole which on both sides goes to the nose, and that, lest that the humors falling from the brain should flow by the nose into the Eyes, as we see it fares with those whose eyes perpetually weep, or water, by reason of the eating away of this glandule, whence that affect is called, the Fistula lacrymalis, or Weeping Fistula.
But there is much fat put between the Muscles of the eye, partly,* 1.6 that the motion of the Eyes might be more quick, in that slipperiness of the fat, as also that the temper and complexion of the Eyes, and chiefly of their nervous parts, might be more constant and lasting, which otherwise by their continual and perpetual motion would be subject to excessive dryness. For nature, for the same reason hath placed Glandules flowing with a certain moisture, neer those parts which have perpetual agitation.