Mikrokosmographia a description of the body of man. Together vvith the controuersies thereto belonging. Collected and translated out of all the best authors of anatomy, especially out of Gasper Bauhinus and Andreas Laurentius. By Helkiah Crooke Doctor of Physicke, physitian to His Maiestie, and his Highnesse professor in anatomy and chyrurgerie. Published by the Kings Maiesties especiall direction and warrant according to the first integrity, as it was originally written by the author.

QVEST. XXIIII. Whether the Organ of Sight be Fiery or Watery.

COncerning the Nature of the Eyes the Platonists & Peripatetiks are at great strife. Plato in Timaeo, because he is perswaded that vision is performed by * 1.1 emission of light from the eyes, doth therefore thinke that the eie is of a fie∣rie Nature. The eies (saith he) do participate of that fire which dooth not burn, but by illumination doth cheerfully drawe the day out of the Dunge∣on of the night. Now Fire according to the Platonists is threefold. First, that which doth both shine and burne: secondly, that which shineth but burneth not. Thirdly, that which burneth but doth not shine. And this opinion of Plato Galen seemeth to follow in his 10. Booke De vsu partium, and in the seuenth De Placitis Hippo. & Platonis. For he calleth the eye a bright organ and the Sun-like part of the creature.

The Reasons of the Platonists be these. First, the eyes of some creatures do shine & glitter in the night, as of Night-Owles and of Cats. Againe, some in vehement fittes of * 1.2 anger haue their eyes as it were burning and enflamed. Moreouer, when the eie is shot at one side, we see a kinde of fierie glaunce like Lightning, and the Eye being rubbed in the darke doth yeelde a bright glimpse vnder the finger. Aristotle affirmeth, that An∣tiphon had his owne shape and Image continually before his eies. And Pliny reports ma∣ny things of Tiberius Caesar in the 11. booke of his Naturall Historie. Galen also in the se∣uenth Booke De Placitis Hippocratis & Platonis maketh mention how it hapned vnto one many nights before he vtterly lost his Sight, that he perceiued a great quantity of light to yssue foorth of his eyes. Furthermore that the eyes be fiery may be thus demonstra∣ted, because they are verie agile, plyable and mooueable: now facility of motion is from heate. They are also translucid of a pyramidall Figure and full of spirits, because they performe their functions in a moment. To these we adde, that to the most noble sensoriū or organ is due the noblest element, which is the fire. Againe, the senses are of the same Nature with the things which are subiected to them: but colours are of a fierie Nature, for so Plato defines colour to be a flame yssuing from the bodie coloured.

Lastly, the eyes neuer grow stiffe as do other parts of the bodie, whence it followeth that they are of a fierie nature. On the contrarie part, Aristotle and all the Peripatetiks do * 1.3 contend that the eye is waterie, but he that desires more satisfaction heerein may reade those things which the same Aristotle writ against the Platonists in his Booke De Sensu & Sensili.

We will subscribe rather to this latter opinion, and the same doth Diuine Hippocrates affirme in his Booke de locis in homine, The Sight is nourished by the humiditie of the Braine. * 1.4 Of the same minde also was Democritus as Aristotle reports in his Booke of Sense. Las•• Anatomie and the whole composition of the eies doth conuince this. For the principall parte of the eye which first of all causeth vision is all ycy, which part being drowned in the glassy humor, hath in the forepart a watery humor so disposed for a defence. And if the eye be hurt or wounded, whatsoeuer doth flowe from it is watery.

Some haue laboured to reconcile Plato with Aristotle after this manner: There be two * 1.5 things to be considered in the eyes which concurre to this act of vision: first a most clear Visiue spirit flowing from the Braine through the Optick Nerues, and secondlie the Cri∣stalline humor. Now according to this distinction they say, that in regard of the spirits & the internall light, as also of the enlightned obiect the eye is fierie, but in regarde of the Cristalline it is watery. But this distinction seemeth not to be altogether tollerable, for so euery organ should be fiery, because the organes of all Senses haue their animall spirites

of the same Nature, tenuity and brightnesse. For there are not diuers kindes of the Ani∣mall spirits; that some should be appointed to the sight, others to Hearing: I therefore hold it better to affirme simply according to Aristotle and indeed the truth it selfe, that the Organ of sight is watery.

Concerning those reasons which are produced in defence of the Platonistes, * 1.6 they be of small moment; for the eyes doe shine indeede, and oftentimes a bright splen∣dour doth proceed from them, but not by reason of the fire, but because of the tralucen∣cie, playnnes and smoothnes of the chrystaline and the coates; for whatsoeuer things are * 1.7 smooth and neate do shine in the dark, as horne. Againe, it hapneth because the externall light receiued of the chrystaline doth not presently vanish. They are mouable & for this cause called by the Poet faciles, yet this is not from the fire but from an aboundant and slip∣ry humidity, from the spirits and the sixe strong muscles, by which it is an easie matter for a small member to be moued.

They are called spirituall by reason of their action, for they perfourme their function * 1.8 in an instant, and because they receiue incorporeall and immateriall species or formes pro∣duced & brought thorough the ayre and continually offering themselues to the Pupilla or Apple. They are not stiffe, yet this is not because they are firy, but as Aristotle teacheth in his Problemes, because they are inuironed with aboundance of fat; which fat though it * 1.9 haue for his efficient cause a defect or weakenesse of heate; yet not withstanding by his reflexion it doth augment the heate, and by his sliminesse doth hinder the ingresse of the ayre which beateth vpon them. To these wee ioyne the plenty of animall spirits, and the perpetuall motions of the eyes.

Notes

• * 1.1

  Plato saith it is fierie.
• * 1.2

  The Plato∣nists reasons.
• * 1.3

  The opinion of Aristotle that the eie is watery.
• * 1.4

  The authority of Hippocrates. Democritus. Reasons.
• * 1.5

  Carpentarius reconciling Aristotle & Pla∣to is reproo∣ued.
• * 1.6

  The reasons of the Plato∣inst•• answered
• * 1.7

  Why the eye doth shine.
• * 1.8

  Why they are called spiritu∣all.
• * 1.9

  Why not stiffe