3 i6 A TREATISE 



properties which render a body impenetrable. A net according- 

 ly we fee, that if a diaphanous body ( which fuftereth light to 

 run through it) be much comprefled bevond what it was ; as 

 when water is ccmprefled intoyce;it becometh more vifible, 

 that is, reflecieth more light : and confequendy , it becometh 

 more white; for white is that, which refle&eth moft Jight. 



On the contrary fide, foftnefle, unduoufneflc, and vifcouf- 

 nefle , encreafeth blacknefle : as you may experience in oyiing 

 or in greafing of wood ; which before was but brown, for there- 

 by it commeth more black ; by reafon that the unctuous parts 

 added unto the other, do more eafily then they fingle, admit in- 

 to them the light that ftriketh upcn them ; and when it is got- 

 ten in, it is fo entangled there (as though the wings of it were 

 birdlimed over) that it cannot fly out againe. And thus it is 

 evident,how the origine of all colours in bodies, is plainly dedu- 

 eed out of the ?arious degrees of rarity and density , varioufly 

 mixed and compounded. 



$. . likewise, out of thisdiicourfe, the reafon is obvious why 

 VVhy forac bo- fome bodies are diaphanous and others are opacous : for fith- 

 ence lt feM ct h out m the constitution of bodies, that one ij com 1 - 1 

 P^ ec ^ ^S KSLtcr P arts f ^ en an oc ^ er : * c mu ^ nee< ^ $ haflpeiri that 

 light be more hindered in paffing through a body Corcfjlofed of 

 bigger parts.then an other who/? pirrs are ic/fe. Neither doth 

 it import that the pores be iuppoiecf as great as the parts, for be 

 they never fo large , the corners of the thiclcc parts they belong 

 unto, muft needs break the cour/c of what will not bow, but 

 goeth all in ttralght lines ; more then if the parts and pores 

 were both JefTer ; fince, for fo fubtile a piercer as light,no pores 

 can be too little to give it entrance. It K true (ucn great ones 

 would better admit a Jiqaid body into them, fach a one as wa- 

 ter or ayre j but the reafon of that is, bffcaufc they will bow and 

 take any ply, to creep into thofe cavities,ifthey be large eneugh, 

 which light will not do. 



There/ore it is cleare, thatfrecdomcofpaflagecan happen 

 unto light, only there, where there is an extreme great multi- 

 tude of pores and parties in a very little quantity or bulke of 

 body (which pores and parts muft confeouently bccxtreme lit- 

 tle ones) for,by reafon of their multitude, there muft be great 

 variety in their (ituation : from whence it will happen that 



many 



