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QVEST. XXX. Whether the light be the obiect of the Sight.
THere be some which do determine that light is the obiect of Sight, groun∣ding their opinion vpon this foundation, because euerie thing which is seen * 1.1 either is light, or it is seene by the light, or as Simplicius saith, that vvhich is seene is either light or nere a Kin vnto it, concluding hence, that light is visi∣ble by it selfe, but colours and other things onely by the meanes of light, in∣somuch as light is the cause wherefore they are seene. But none of these are true, & first of all that proposition may not be granted, to wit, that whatsoeuer is seene is either light or is seene by the light, or is very like to it. For if they take Seeing in so large a sense as to perceiue a thing with the Eyes (as it is necessary that they must grant, for else we will denie that the light it selfe may be seene) then would also darknesse it selfe be seene, which ney∣ther is nor may be seene by the light, neyther is it of a nature like vnto it.
Again, all things are not seene by light, for there are somethings which are made con∣spicuous * 1.2 onely by darknesse, but in too cleere and splendide a light they flye from the Sense, as the Scales and eyes of Fishes, olde rotten wood, yea I say the Stars themselues, which therefore the vulgar imagine do fall because they be obscured by the light of the Sunne and so taken from our sight, but at the returne of the Euening twylight, (to wit) * 1.3 vvhen the light goeth avvay and the night approcheth they are by degrees restored to our sight again, as in the morning tvvylight they after the same manner doe vvithdravv them∣selues by little and little from vs. Therfore euery thing vvhich is seen is not light or seen by the light.
Reason and Aristotles doctrine doe contradict this opinion: for vvee are taught by both these that the Eye should be free from his owne obiect, that so it may receiue it more * 1.4 sincerely, but the Eye both in regard of his whole frame and composition and especially in respect of the cristalline humour, where the reception of the obiect is properly made is especially light and cleare, light therefore cannot be the obiect of the Sight.
Moreouer, to see, is not onely to know a thing with the Eyes (for this is too large a a signification, and agreeth to many things beside the proper obiect) but wee doe properly see that in which (when it is perceiued with the Eye) the sight is determined and stayeth it selfe. But the sight is not terminated in the light, though the Eyes doe perceiue it but reach∣eth alwayes beyond it. Seeing therefore the light cannot be truely seene, it canot bee the true obiect of Sight.
Furthermore, an incorporeall obiect cannot alter a corporeal. Organ, except it pro∣ceede * 1.5 from a body, that is, be a quality thereof, and then that alteration is attributed to the body by the meanes of the quality; but that vision be made it is necessary that the Organ be altered by the obiect; the light therfore because it is a bare quality (though they deny this) is not to be thought the obiect of Sight, but some other corporeall body wherein there is a visible quality.
Lastly, the Organ ought to bee potentially that which the Obiect is actually, but the * 1.6 light is actually incorporeall, and no corporeall body is potentially incoporeall, vnlesse by the means of some actiue qualities, but no such actiue powes proceedeth from the light but illuminatiue and enlightning, which they think hath the Nature of an Obiect. But they stil obiect that al visible things must be reduced vnto som primary genus, which may be cal∣led an obiect. Seeing therefore light is the first of all, because by the helpe thereof others things are seen, but light needeth no other helpe, therefore worthily all other visible things ought to bee referred vnto light as vnto their primary and chiefe genus, and so it re∣maineth that light is the first and proper obiect of Sight.
But besides that it is denyed that all visible things are seene by the helpe of Sight, as * 1.7 we sayd before, yet though we should grant so much it would not follow that all obiects are to be referred vnto the light as to their first and chiefe Genus. For visible things are not therefore seene, because they are illustrated and made bright by the light, but because they haue another affection which can alter the Visiue faculty. Wee grant therefore that light doth necessarily concurre vnto vision, but we deny that it is the immediate cause ther∣of. Moreouer, it is true that those things which mooue the visiue Faculty ought to * 1.8 be reduced to some one principall genus which is called an Obiect. Yet all visible things both proper and inproper with all which do any wayes fall vnder the Sight cannot be reser∣ued vnto any one genus and therefore not vnto light.