Chap. TO. esfTrettife of BODIES. 101 



But we rauft take heed of considering fuch gravity and levity 

 as ifthcy were Entities that work fuch effects : fiuce upon exa- 

 mination, it appcareth that thefe words are butfhort exprefTi- 

 ons of the efftds thcmfclves : the caufes whereof, the vulgar of 

 mankind ( u ho impefc names to things ) do not confider ; but 

 leave that work unto Philofophcrs to examine ; whiles they 

 onely obferve, what they fee done ; and agree upon words to 

 cxpreflc thac. Which words neither will in all circumstances 

 alwaycs agree to the fame thing ; for as cork doth defcend in 

 aire and afcend in water; fo alfo will any other body defcend if 

 it lightcth among others more rare then it fclf, and will afcend 

 ifit lightcth among bodies that arc more denfe then it. And we 

 term bodies light and heavy, onely according to the courfe, 

 which we ufually fee them take. 



Now proceeding further on ; and confidering how there are 

 various degrees of denfity or gravity: it were irrationall to the mor'e denfe 

 conceive, that all bodies fhould defcend at the fame rate, and * bod V\^ e - 



. , , .... more fwihly it 



keep equall pace with one another, in their journey down- defccnJcth. 

 wards. For as two knifes whereof one hath a keener edge then 

 the other, being prefled with equall ftrength into like yielding 

 matter, the {harper will cut deeper then the other : fo, if of 

 two bodies one be more denfe then the other ; that which is Co, 

 will cut the aire more powerfully, and will defcend fafter thea 

 the otherrfor in this caie denfity may be compared to the knifes 

 edge, fince in it confifteth the power of dividing ; as we have 

 heretofore determined. And therefore, the prcffing them down- 

 wards by the defcending atomes, being equall in both (or per- 

 adventure greater in the more denfe body; as anon we (hall 

 have occafion to touch ) and there being no other caufe to de- 

 termine them that way ; the eflfcft of divifion muft be the grea- 

 ter, where the divider is the more powerful!. Which, the more 

 denfe body is ; and therefore cutteth more ftrongly through the 

 refinance of the aire ; and confequemly, pafleth more Iwiftly g. 

 that way it is determined to move. The velocity of 



I do not mean, that the velocities of their defcent (hall be in !T d ' C j de . fcen 



t /- L L j r r dln & doth not 



the fame proportion to one another, as their denn ties are : for encreafc in pro. 

 befides their dcnfiry, thofe other confiderations which we have 5?ftn [hsu 

 difcourfcd of above when we examined the caules of velo- maybe between 

 city in motion, muft likewife be ballanced. And out of the 



G 5 com- 



