[oo] The glorious Landskips, and other Objects that present themselves to the Eye, are manifestly painted on the Retina, and that not erect, but inverted as the Laws of Opticks require; and is manifest to the Eye from Monsieur Cartes’s Experiment, of laying bare the vitreous Humour on the back part of the Eye, and clapping over it a Bit of white Paper, or the Skin of an Egg; and then placing the fore-part of the Eye to the Hole of the Window of a darkned Room. By which means we have a pretty Landskip of the Objects abroad invertedly painted on the Paper, on the back of the Eye. But now the Question is, How in this Case the Eye comes to see the Objects erect? Monsieur Cartes’s Answer is, Notitia illius ex nullâ imagine pendet, nec ex ullâ actione ab objectis veniente, sed ex solo situ exiguarum partium cerebri, è quibus Nervi expullulant.——E.g. cogitandum in Oculo——situm capillamenti nervi optici——respondere ad alium quendam partis cerebri——qui facit ut Anima singula loca cognoscat, quæ jacent in rectâ, aut quasi rectâ lineæ; ut ita mirari non debeamus corpora in naturali situ videri, quamvis imago in oculo delineata contrarium habeat. Dioptr. c. 6. But our most ingenious Mr. Molyneux answereth thus, The Eye is only the Organ or Instrument, ’tis the Soul that sees by means of the Eye. To enquire then how the Soul perceives the Object erect, by an inverted Image, is to enquire into the Soul’s Faculties——But erect and inverted are only Terms of Relation to up and down; or farther from, or nigher to the Center of the Earth, in Parts of the same Thing.——But the Eye, or visive Faculty takes no notice of the internal Posture of its own Parts, but useth them as an Instrument only, contrived by Nature for the Exercise of such a Faculty.——Let us imagine, that the Eye (on its lower Part) receives an Impulse [by a Ray from the upper part of the Object] must not the visive Faculty be necessarily directed hereby to consider this Stroke, as coming from the top rather than the bottom [of the Object] and consequently be directed to conclude it the Representation of the top? Hereof we may be satisfied, by supposing a Man standing on his Head. For here, though the upper Parts of Objects are painted on the upper Parts of the Eye, yet the Objects are judged to be erect. What is said of Erect and Reverse, may be understood of Sinister and Dexter. Molyneux’s Dioptr. Nov. Part I. Prop. 28.
CHAP. III.
Of the Sense of Hearing.
Concerning the Sense of Hearing, I shall take notice of two Things, the Organ, the Ear; and its Object, Sound.
I. For the Organ, the Ear; I shall pass by its convenient Number of being double, which (as in the last Sense) serves for the commodious Hearing every way round us; as also a wise Provision for the utter Loss or Injury[a] of one of the Ears. But I shall a little insist upon its Situation, and its admirable Fabrick and Parts.
1. It is situated in the most convenient Part of the Body, (like as I said the Eye is) in a Part near the common Sensory in the Brain, to give the more speedy Information; in a Part where it can be best guarded, and where it is most free from Annoyances and Harms it self, and where it gives the least Annoyance and Hindrance to the Exercises of any other Part; in a Part appropriated to the peculiar Use of the principal Senses, in the most lofty, eminent Part of the Body, where it can perceive the most Objects, and receive the greatest Information: And lastly, in a Part in the Neighbourhood of its Sister Sense the Eye, with whom it hath peculiar and admirable Communication by its Nerves, as I intend to shew in its proper Place. In respect then of its Situation and Place in the Body, this Sense is well designed and contrived, and may so far be accounted the Work of some admirable Artist. But,
2. If we survey its Fabrick and Parts, it will appear to be an admirable Piece of the Divine Wisdom, Art, and Power. For the Manifestation of which, let us distinctly survey the outward and the inward Part of its curious Organ.
1. For the outward Ear: If we observe its Structure in all Kinds of Animals, it must needs be acknowledged to be admirably Artificial, it being so nicely prepared, and adjusted to the peculiar Occasions of each respective Animal. In Man[], it is of a Form proper for the erect Posture of his Body. In Birds, of a Form proper for Flight; not protuberant, because that would obstruct their Progress, but close and covered, to afford the easier Passage through the Air. In Quadrupeds, its Form is agreeable to the Posture, and slower Motion of their Bodies; and in these too, various, according to their various Occasions. In some large, erect, and open, to hear the least Approaches of Dangers[c], in others covered, to keep out noxious Bodies. In the Subterraneous Quadrupeds, who are forced to mine, and dig for their Food and Habitation, as a protuberant Ear, like that of other Quadrupeds, would obstruct their Labours, and be apt to be torn and injured; so they have the contrary[d], their Ears short, lodged deep and backward in their Head, and passing to the under Part thereof, and all sufficiently fenced and guarded. And as for Insects, Reptiles, and the Inhabitants of the Waters, if they enjoy this Sense, (as there is great Reason to think they do,) it may probably be lodged commodiously under the same Security and Guard, as the Smelling, or some other Sense is.