94 MEMOIR OF DR. DALTON, AND 



* Moreover, since food augments and nourishes 



the body, we may understand that veins and blood, and bones, and 

 nerves consist of heterogeneous parts. Or if they shall say, that all 

 food IS of a mixed substance, and contains in itself small elements of 

 nerves and bones, and also veins and particles of blood, it will follow 

 that both all solid food, and liquid itself, must be thought to consist 

 of such heterogeneous matter, and be mixed up of bones and nerves, 

 and veins and blood. Besides, if whatever bodies grow from the 

 earth are previously in the earth, earth must consist of all these 

 heterogeneous matters which spring from the earth." 



He gets however into a similar difficulty, by saying that 

 the atoms which make up these substances, have primary 

 particles of a different figure. 



* " Finally, if you think that whatever things you see in the visible 

 world, could not have been formed without supposing the primary 

 particles of matter to be endowed, with a nature similar to the things 

 formed from them, your original elements of things by this hypothesis 

 fall. For the consequences will be that you must have primary 

 particles of matter, which, being the origin of laughter, are themselves 

 convulsed with tremulous fits of laughter, and others which bedew 

 their own faces and cheeks with salt tears." 



As to forces, he says : — 



f " For certainly neither the primary elements of things disposed 

 themselves severally, in their own order by their own counsel or 

 sagacious understanding; nor assuredly did they agree among 

 themselves, what motions each should produce ; but because being 

 many, and changed in many ways, they are for an infinite (space 

 of time) agitated, being acted upon by forces, throughout the whole, 

 they thus by experiencing movements, and combinations of every 

 kind, at length settle into such positions, by which means, this sum 

 of things produced, exists." 



He speaks again of their being moved of themselves, and 

 urged by secret impulse ; and gives their original motion to 

 be a falling straight down, not in a right line. For if they 



• 1. 914. t 1. 1020. 



