90 MEMOIR OF DR. DALTON, AND 



iron glows in the fire ; rocks often burst with fervent heat ; the 

 hardness of gold, losing its firmness, is often dissolved by heat ; 

 the icy coldness of brass, overcome by flame, melts ; heat and pene- 

 trable cold enter into silver, for we Kave felt both with our hand, 

 when, as we held cups straight in the hand, water was poured 

 into them from above, so that as far as these instances go there is 

 nothing solid in nature. But because, however, right, reason, and 

 the nature of things, compel (me to hold a different opinion,) grant 

 me your attention until I make it plain in a few verses, that there 

 really exist such bodies as are of a solid and eternal corporeal 

 substance, which bodies we prove to be seeds and primary particles 

 of things, of which the whole generated universe now consists." 



" In the first place, since a two-fold nature of two things ex- 

 tremely dissimilar has been found to exist, viz., matter and space, in 

 which everything is done, it must necessarily be that which exists 

 by itself for itself, and pure (free from mixture) ; for wheresoever 

 there is empty space, which we call a vacuum, there is no matter ; 

 and likewise wheresoever matter maintains itself, there by no means 

 exists empty space. Original substances are therefore solid, and 

 without vacuity. 



" Furthermore, since in things that are produced there is empty 

 space, solid matter must exist around it ; nor can anything be proved 

 by just argument to conceal vacuity, and to contain it within its 

 body, unless we admit that which contains it to be a solid. But 

 that solid can be nothing but a combination of matter, such as may 

 have the power of keeping a vacuity enclosed. Matter, therefore, 

 which consists of solid body may be eternal, while other substances 

 may be dissolved (or cease to be). In addition, too, if there were 

 no space to be vacant and unoccupied all would be solid. On the 

 other hand, unless there were certain bodies to fill up completely the 

 spaces which they occupy, all space which exists must be an empty 

 word. Body, therefore, is evidently distinct from empty space. 



'* These bodies (which thus fill up empty space) can neither be 

 broken in pieces by being struck with bodies externally, nor again 

 can be decomposed by being penetrated internally ; nor can they be 

 made to yield, if attempted, by any other method, which we have 

 demonstrated to you a little above ; for neither does it seem possible 



