Note kk — BOOK IV.

Palpebræ, quæ sunt tegumenta Oculorum, mollissimæ tactu, nè lederent aciem, aptissimæ factæ, & ad claudendas Pupillas, nè quid incideret, & ad aperiendas; idque providit, ut identidem fieri posset cum maximâ celeritate. Munitæque sunt Palpebræ tanquàm vallo pilorum: quibus & apertis Oculis, si quid incideret, repelleretur, & somno conniventibus, cùm Oculis ad cernendum non egerimus, ut qui, tanquàm involuti, quièscerent. Latent prætereà utiliter, & excelsis undique partibus sepiuntur. Primùm enim superiora Superciliis obducta sudorem à capitæ, & fronte destuentem repellunt. Genæ deinde ab inferiore parte tutantur subjectæ, leviterque eminentes. Cicer. de Nat. Deor. L. 2. c. 57.

Tully, in the Person of a Stoick, having so well accounted for the Use of the Eye-Lids, I shall for a further Manifestation of the Creator’s Contrivance and Structure of them, take notice of two or three Things: 1. They consist of a thin and flexible, but strong Skin, by which means they the better wipe, clean, and guard the Cornea. 2. Their Edges are fortified with a soft Cartilage, by which means they are not only enabled the better to do their Office, but also to close and shut the better. 3. Out of these Cartilages grow a Pallisade of stiff Hairs, of great Use to warn the Eye of the Invasion of Dangers, to keep off Motes, and to shut out too excessive Light, &c. and at the same time to admit of (through their Intervals) a sufficient Passage for Objects to approach the Eye. And it is remarkable, that these Hairs grow but to a certain, commodious Length, and need no cutting, as many other Hairs of the Body do: Also, that their Points stand out of the way, and in the upper-lid bend upwards, as they do downwards in the lower lid, whereby they are well adapted to their Use. From which last Observables, we may learn how critical and nice the great Author of Nature hath been, in even the least and most trivial Conveniencies belonging to Animal Bodies; for which Reason I have added it to Tully’s Remarks. And more might have been added too, as particularly concerning the curious Structure and Lodgment of the Right Muscle, which opens the Eye-Lids; and the Orbicularis, or Circular one, that shuts them; the nice Apparatus of Glands that keep the Eye moist, and serve for Tears; together with the Reason why Man alone, who is a social Animal, doth exhibit his social Affections by such outward Tokens as Tears; the Nerves also, and other Organs acting in this Ministry. I might also speak of the Passages for discharging the superfluous Moisture of the Eyes through the Nostrils, and much more of the like kind. But it would take up too much Room in these Notes; and therefore it shall suffice to give only such Hints as may create a Suspicion of a noble Œconomy and Contrivance in this (I had almost said) least considerable part of the Eye. But for Particulars I shall refer to the Anatomists; and for some of these Things, particularly to Dr. Willis’s Cereb. Anat. and de Anim. Brut. and Mr. Cowper’s Elegant Cuts in the 11ᵗʰ Tab. of his Anatomy.

To the Eye-Lids we may add another Guard afforded the Eyes of most Quadrupeds, Birds, and Fishes, by the nictitating Membrane, which Dr. Willis gives this Account of, Plurimis [Animalibus] quibus Musculus suspensorius adest (which Limitation he needed not to have added) etiam alter Membranosus conceditur, qui juxta interiorem oculi canthum situs, quando elevatur, Oculi globum ferè totum obtegit. Hujus usus esse videtur, ut cùm Bestiæ inter gramina, &c. capita sua propter victum capessendum demergunt, hic Musculus Oculi Pupillam, nè à stipularum incursu seriatur, oculit, munitque. De Anim. Brut. p. 1. c. 15.

This Membrane Man hath not, he having little Occasion to thrust his Head into such Places of Annoyance, as Beasts and other Animals; or if he hath, he can defend his Eyes with his Hands. But Birds (who frequent Trees and Bushes) and Quadrupeds, (Hedges and long Grass) and who have no part ready, like the Hand, to fence off Annoyances; these, I say, have this incomparable Provision made for the Safety of their Eyes. And for Fishes, as they are destitute of Eye-Lids, because in the Waters there is no occasion for a Defensative against Dust and Motes, offensive to the Eyes of Land Animals, nor to moisten and wipe the Eyes, as the Eye-Lids do, so the Nictitating-Membrane is an abundant Provision for all their Occasions, without the Addition of the Eye-Lids.

And now, if we reflect, are these the Works of any Thing but a wise and indulgent Agent?