Physiologia Epicuro-Gassendo-Charltoniana, or, A fabrick of science natural, upon the hypothesis of atoms founded by Epicurus repaired [by] Petrus Gassendus ; augmented [by] Walter Charleton ...

SECT. I.

AMong the many different Concepti∣ons of Philosophers, both Ancient and Modern, touching the Manner and Reason of the Discernment of the Magnitude, Figure, &c. of Vi∣sible Objects by the Visive Faculty in the Eye; the most Considerable are these.

(1) The STOICKS affirmed,* 1.1 that certain Visory Rayes deradia∣ted from the brain, through the slender perforations of the Optick Nerves, into the eye, and from thence in a continued fluor to the object; do, by a kind of Procusion, and Compression, dispose the whole Aer intermediate in a direct line, into a Cone, whose Point consisteth in the superfice of the Eye, and Base in the su∣perfice of the Object. And that, as the Hand by the mediation of a staff, imposed on a body, doth, according to the degrees of resistence made there∣by either directly, or laterally, deprehend the Tactile Qualities thereof, i. e. whether it be Hard, or Soft, Smooth or Rough, whether it be Clay, or Wood, Iron, or Stone, Cloth, or Leather, &c. So likewise doth the Eye, by the mediation of this Aereal staff, discern whether the Adspectable Ob∣ject, on which the Basis of it resteth, be White or Black, Green or Red, Sy∣metrical or Asymetrical in the Figure of its parts, and consequently Beauti∣ful or Deformed.

* 1.2(2) ARISTOTLE, though his judgment never acquiesced in any one point, as to this particular, doth yet seem to have most constantly incli∣ned to this; that the Colour of the Visible doth move the Perspicuum actu, i. e. that Illustrate Nature in the Aer, Water, or any other 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, Transparent body; and that, by reason of its Continuity from the extremes of the Object to the Eye, doth move the Eye, and by the mediation there∣of the Internal Sensorium or Visive Faculty, and so inform it of the visible Qualities thereof. So that, according to the Descant of those, who pre∣tend to be his most faithful Interpreters, we may understand Him, to have imagined the Colour of the object to be as it were the Hand; the diaphanous Medium as it were the Staff; and the Eye as it were the Body on which it is imposed and imprest: è diametro opposite to the conceit of the Stoicks, who suppose the Eye to supply the place of the Hand; the Aer to analogize the Staff; and the Object to respond to the Body on which it is imposed and imprest.

* 1.3(3) The PYTHAGOREANS determined the reason of Vision on the Reflexion of the Visive Rayes, in a continued stream emitted from the internal Eye, to the visible, back again into the eye; or, more plainly, that the radious Emanations from the Eye, arriving at the superfice of the object, are thereby immediately Repercussed in an uninterrupted stream home again to the eye, in their return bringing along with them a perfect representati∣on thereof, as to Colour, Figure and Magnitude.

* 1.4(4) EMPEDOCLES, though admitting (as we hinted in the next praeceding Chapter) substantial Effluxes, from the Visible to the Organ of Sight; doth also assume the Emission of certain Igneous or Lucid Spi∣rits from the Organ to the Object: supposing the Eye to be a kind of Glass Lantern, illustrate, and illustrating the Visible, by its own Light.

* 1.5(5) PLATO, though He likewise avouched the Emanation of Cor∣poreal Effluviaes from the Object; doth not yet allow them to arrive quite home at the Eye: but will have them to be met half way by rayes of Light extramitted from the Eye: and that these two streams of External and Internal Light encountring with some Renitency reciprocal, do recoyl each from other, and the stream of Internal Light resilient back into the eye, doth communicate unto it that particular kind of Impression, which it received from the stream of Extradvenient Light, in the encounter; and so the Sentient Faculty comes to perceive the adspectable Form of the object, at which the Radius of Internal Light is levelled. This we judge to be sense of his words (in Timaeo, circa finem tertiae partis) Simulachrorum, quae vel in speculis oboriuntur, vel in perspicua, laevi{que} cernuntur superficie; facilis asse∣cutio est. Nam ex utrius{que} ignis, tam intimi, quam extra positi Communio∣ne, ejus{que} rursus consensu, & congruentia, qui passim terso, laevi{que} corpori accommodatus est; necessari•• haec omnia oriuntur, quam ignis oculorum cum eo igne, qui est è conspecto effusus, circa laeve nitidum{que} Corpus sese con∣fundit.

* 1.6(6) EPICURUS, tacitely subverting all these, foundeth the Reason of Vision, not in any Action of the intermediate Aer, as the Stoicks and Aristotle; nor in any Radious Emanation from the Eye to or toward the

Object, as the Pythagoreans, Empedocles, and Plato: but, in the Deriva∣tion of a substantial Efflux from the Object to the Eye.

(7) And as for the opinion of the excellent Monsieur Des Cartes,* 1.7 which with a kind of pleasant violence, hath so ravisht the assent of most of the Students of Physiology, in the praesent Age, especially such as affect the accommodation of Mechanick Maxims to the sensible operations of Nature; that their minds abhor the embraces of any other: those, who have not heed∣fully perused his Dioptricks, may fully comprehend it in summary, thus.

For Sensation in Common, He defines it to be a simple Perception, where∣by a certain Motion, derived from a body conveniently objected, communi∣cated, by Impression, to the small Fibres, or Capillary Filaments of a Nerve, and by those, in regard of their Continuity, transmitted to the Tribunal, or Judicatory Seat of the Soul, or Mind (which He supposeth to be the Glandula Pinealis, in the centre of the Brain) and there distinctly apprehended, or judged of. So that the Divers Motions imprest upon the slender threads of any Nerve, are sufficient to the Causation of divers perceptions; or, that we may not eclipse his notion by the obscurity of our Expression, that the Impulse, or stroke given to the Nerve, doth, by reason of the Continui∣ty of its parts, cause another Motion, in all points answerable to the first re∣ceived by the External Organ, to be carried quite home to the Throne of the Mind, which instantly makes a respective judgment concerning the Na∣ture of the Object, from whence that particular Motion was derived. In a word, that only by the Variety of Strokes given to the External Organ, thence to the filaments of the Nerve annexed thereto, thence to the Prae∣sence Chamber of the Soul: we are informed of the particular Qualities, and Conditions of every Sensible; the variety of these sensory Motions being dependent on the variety of Qualities in the Object, and the variety of judgments dependent on the variety of Motions communicate.

And for the sense of Seeing, in special; He conceives it to be made, not by the mediation of Images, but of certain Motions (whereof the Images are composed) transmitted through the Eye and Optick Nerve to the Cen∣trals of the Brain: praesuming the Visible Image of an Object to be only an exact representation of the motions thereby impressed upon the External Sensorium; and accordingly determining the Reason of the Minds actual Discernment of the Colour, Situation, Distance, Magnitude, and Figure of a Visible, by the Instruments of Sight, to be this. (1) The Light desilient from the adspectable Body, in a direct line, called by the Masters of the Opticks, the Axe of Vision, percusseth the diaphanous fluid Medium, the Aether, or most subtile substance (by Him assumed to extend in a Continu∣ate Fluor through the Universe, and so to maintain an absolute Plenitude, and Continuity of Parts therein.) (2) The Aether thus percussed by the Illu∣minant, serving as a Medium betwixt the Object and the Eye; conveyeth the impression through the outward Membranes and Humors, destined to Refraction, to the Optick Nerve most delicately expansed into the Retina Tunica, beyond the Chrystalline. (3) The Motion thus imprest on the outward Extreme of the Optick Nerve, runs along the body of it to the inward Extreme, determined in the substance of the Brain. (4) The Brain receiving the impression, immediately gives notice thereof to its Noble Te∣nent,

the Soul; which by the Quality of the stroke judgeth of the Quality of the Striker, or Object. In some proportion like an Exquisite Musitian, who by the tone of the sound thereby created, doth judge what Cord in a Virginal was strook, what jack strook that string, and what force the jack was moved withall, whether great, mean, or small, slow or quick, equal or unequal, tense or lax, &c.

* 1.8This you'l say, is a Conceit of singular Plausibility, invented by a Wit transcendently acute, adorned with the elegant dress of most proper and significant Termes, illustrate with apposite similes and praegnant Examples, and disposed into a Method most advantageous for persuasion; and we should betray our selves into the Censure of being exceedingly either stupid, or malicious, should we not say so too: but yet we dare not (so sacred is the in∣terest of Truth) allow it to be more then singularly Plausible; since those Arguments, wherewith the sage Digby (in the ••2. chap. of His Treatise of Bodies) hath long since impugned it, are so exceedingly praeponderant, as to over-ballance it by more then many moments of Reason; nor could Des Cartes himself, were He now Unglorified, satisfie for his Non-Retractation of this Error; after his examination of their Validity, by any more hopeful Excuse, then this; that no other opinion could have been consistent to His Cardinal Scope of Solving all the Operations of Sense by Mechanick Prin∣ciples.

Now, of all these Opinions recited, we can find, after mature and aequi∣table examination,* 1.9 none that seems, either grounded on so much Reason, or attended with so few Difficulties, or so sufficient to the verisimilous Ex∣planation of all the Problems, concerning the Manner of Vision, as that of Epicurus; which stateth the Reason of Vision in the INCURSION of substantial Images into the Eye. We say

FIRST, Grounded on so much Reason. For, insomuch as it is indisputa∣ble, that in the act of Vision there is a certain Sigillation of the figure and colour of the object, made upon that part of the Eye, wherein the Perception is; and this sigillation cannot be conceived to be effected otherwise then by an Impression; nor that Impression be conceived to be made, but by way of Incursion of the Image, or Type: it is a clear Consequence, that to admit a Sigillation without Impression, and an Impression without Incursion of the Image, is a manifest Alogy, an open Inconsistence. And upon this conside∣ration is it, that we have judged Epicurus to have shot nearest the White, in his Position that Vision is performed, 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, per simula▪ chrorum Incursionem, sive Incidentiam: which Agellius (lib. 5. cap. 16.) de∣scanting upon, saith expresly, Epicurus affluere semper ex omnibus corporibus simulachra quaedam ipsorum, eaque sese in oculos inferre, atque ita fieri sensum videndi putat.

SECONDLY, Encumbred with so few Difficulties. For, of all that have been hitherto, either by Alexander (2. de Anima 34.) Macrobius (7. Sa∣turnal. 14.) Galen (lib. 7. de Consensu in Platonicis, Hippocraticisque Decretis) or any other Author, whose leaves we have revolved, objected against it; we find only Two, that require a profound exercise of the Intellect to their Solution: and they are these.

(1) Obvious it is even to sense,* 1.10 that every Species Visible is wholly in the whole space of the Medium, and wholly in every part thereof; since in what part soever of the Medium, the Eye shall be admoved, in a position convenient, it shall behold the whole object, represented by the species: and manifest it is, that to be total in the total Space, and total in every part thereof, is an Affe∣ction proper only to Incorporeals; therefore cannot Vision be made by Corpore∣al Images incurrent into the Eye.

(2) In the intermediate Aer are coexistent the Images of many, nay innu∣merable Objects; which seems impossible, unless those Images are praesumed to be Incorporeal: because many Bodies cannot coexist in one and the same place, without reciprocal penetration of Dimensions, Ergo, &c.

Notes

• * 1.1

  Art. 1. The Reason of Vision, accor∣ding to the o∣pinion of the Stoicks.
• * 1.2

  Art. 2. Of Aristotle.
• * 1.3

  Art. 3. O the Phytha∣goreans.
• * 1.4

  Art. 4. Of Empedocles.
• * 1.5

  Art. 5. Of Plato.
• * 1.6

  Art. 6. O Epicurus.
• * 1.7

  Art. 7. Of Mons. Des Cartes.
• * 1.8

  Art. 8. The i••genuity of 〈◊〉〈◊〉 Conceit, ac∣knowledged: but the solidi∣ty ••••dubitated
• * 1.9

  Art. 9. The Opinion of Epicurus, more satisfa∣ctory, then any other: because more Rational, and less obno∣xious to inex∣plicable Diffi∣culties.
• * 1.10

  Art. 10. The Two most considerable Difficulties op∣posed to Epi∣curus position, of the Incur∣sion of Sub∣stantial Images into the Eye.