PART. II.
Of the Nature of Whiteneſs and Blackneſs.
CHAP. I.
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Hough after what I have acknowledged, Pyrophilus, of the Abſtruſe Nature of Colours in particular, you will eaſily believe, that I pretend not to give you a Satisfactory account of Whiteneſs and Blackneſs; Yet not wholly to fruſtrate your Expectation of my offering ſomething by way of Specimen towards the Explication of ſome Colours in particular,
I ſhall make choice of Theſe as the moſt Simple Ones, (and by reaſon of their mutual Oppoſition the Leaſt hardly explicable) about which to preſent you my Thoughts, upon condition you will take them at moſt to be my Conjectures, not my Opinions.
2. When I apply'd my Self to conſider, how the cauſe of Whiteneſs might be explan'd by Intelligible and Mechanical Principles, I remembred not to have met with any thing among the Antient Corpuſcularian Philoſophers, touching the Quality we call Whiteneſs, ſave that Democritus is by Ariſtotle ſaid to have aſcrib'd the Whiteneſs of Bodies to their Smoothneſs, and on the contrary their Blackneſs to their Aſperity.[a]6] But though about the Latter of thoſe Qualities his Opinion be allowable, as we ſhall ſee anon, yet that he heeds a Favourable Interpretation in what is Deliver'd concerning the Firſt, (at leaſt if his Doctrine be not Mis-repreſented in this point, as it has been in many others) we ſhall quickly have Occaſion to manifeſt. But amongſt the Moderns, the moſt Learned Gaſſendus in his Ingenious Epiſtle publiſh'd in the Year 1642. De apparente
Magnitudine ſolis humilis & ſublimis, reviving the Atomical Philoſophy, has, though but Incidentally, deliver'd ſomething towards the Explication of Whiteneſs upon Mechanical Principles: And becauſe no Man that I know of, has done ſo before him, I ſhall, to be ſure to do him Right, give you his Senſe in his own Words:[a]7] Cogites velim (ſays he) lucem quidem in Diaphano nullius coloris videri, ſed in Opaco tamen terminante Candicare, ac tantò magis, quantò denſior ſeu collectior fuerit. Deinde aquam non eſſe quidem coloris ex ſe candidi & radium tamen ex eâ reflexum verſus oculum candicare. Rurſus cum plana aquæ Superficies non niſi ex una parte eam reflexionem faciat: ſi contigerit tamen illam in aliquot bullas intumeſcere, bullam unamquamque reflectionem facere, & candoris ſpeciem creare certa Superficiei parte. Ad hæc Spumam ex aqua pura non alia ratione videri candeſcere & albeſcerere quam quod ſit congeries confertiſſima minutiſſimarum bullarum, quarum unaquæque ſuum radium reflectit, unde continens candor alborve apparet. Denique Nivem nihil aliud videri quam ſpeciem puriſſimæ ſpumæ ex bullulis quam minutiſſimis & confertiſſimis cohærentis. Sed ridiculam me exhibeam, ſi tales meas nugas uberius proponem.