432 THOUGHTS ON THE 



For these are of the nature of a powder, but an atom, as 

 Democritus said himself, no one either has seen or can pos 

 sibly see. But this dispersion of substance presents itself 

 in a still more surprising light in odours. For if a little 

 saffron can tinge and impregnate a whole cask of water, a 

 little civet does so to a spacious chamber, and to a second, 

 and a third successively. And let none imagine that odours 

 can be propagated like light, or heat and cold, without a 

 stream of effluvia from the substance, since we may observe 

 that odours are tenacious of solids, of woods, of metallic 

 substances, and for no inconsiderable time, and that they 

 can be extracted and cleansed away from these, by the 

 process of rubbing and washing. But that in these and 

 similar cases, the subtilization is not carried to infinity, no 

 man in his senses will dispute, since this sort of radiation 

 or diffusion is confined to certain spaces, and local boun 

 daries, and to certain quantities of substance, as is very 

 conspicuous in the abovementioned instances. 



As relates to atom in its second sense, which presupposes 

 the existence of a vacuum, and builds its definition of atom 

 on the absence of the vacuum ; it was an excellent and 

 valuable distinction which Hero so carefully drew, when he 

 denied the existence of a vacuum coacervatum (or fully 

 formed), and affirmed a vacuum commistum (or interstitial 

 vacuum). For when he saw that there was one unbroken 

 chain of bodies, and that no point of space would be disco 

 vered or instanced, which was not replenished with body; 

 and much more, when he perceived that bodies weighty and 

 massive tended upwards, and as it were repudiated and 

 violated their natures rather than suffer complete disruption 

 from the contiguous body; he came to the full determina 

 tion that nature abhorred a vacuum of the larger descrip 

 tion, or a vacuum coacervatum. On the other hand, when 

 he observed the same quantity of matter composing a body 

 in a state of contraction and coarctation, and again in one 

 of expansion and dilatation, occupying and filling unequal 

 spaces, sometimes smaller, sometimes greater, he did not see 

 in what manner this going out and in of corpuscles, in 

 reference to their position in that body, could exist, except 

 in consequence of an interspersed vacuum, contracting on 

 the compression, and enlarging on the relaxation, of the 

 body. For it was clear that this contraction of necessity 

 was produced in one of three ways ; either in that which 

 we have specified, namely, the expulsion of a vacuum by 

 means of pressure, or the extrusion of some other body 



