122 Dr. E. J. Mills on the Atomic Theory. 



hence all the parts in quantity must be indivisible. But this 

 assertion is encountered by the following dilemma. If indivisibles 

 make quantity, either a finite or infinite number of them must 

 do so. If a finite number, select as an instance three indivisi- 

 bles, add them together, and make a line (whose extent being 

 only longitude is the first and simplest species of quantity, and 

 therefore whatever is susceptible of partition must be at least a 

 line) . Now, by the conditions, this line cannot be divided into 

 more parts than three ; yet Euclid (Elements, VI. Prop, 10) 

 has demonstrated that a line can be divided into any number of 

 parts, however great. Therefore it is evident that no line, still 

 less any more complex species of quantity, consists of indivisibles. 



Now, Euclid' s demonstration being universal, and proving 

 that all extension can be divided infinitely into parts, we must 

 needs confess that it is of the nature of indivisibles, when they 

 coalesce, to be drowned in one another; for otherwise there 

 would result a kind of extension out of them that would be in- 

 divisible, contrary to the demonstration referred to. But if 

 these indivisibles (even if infinitely numerous) are drowned in 

 one another, they shrink to a single indivisible point. On the 

 other hand, the nature of extension requires that one part be 

 not in the same place where the other is. Therefore quantity 

 cannot consist of an infinite number of indivisibles ; and it has 

 been shown that it is not constituted of a finite number. The 

 dilemma terminates; and it is proved that quantity does not 

 consist of indivisibles (either finite or infinite in number), and, 

 consequently, that parts are not actually in it. 



With this answer to a molecular or atomic theorist, it might 

 have been supposed that our acute and critical reasoner would 

 have been content to relinquish the argument. Yet he lingers a 

 little about it to discuss a difficulty, apparently raised by Sense: — 

 Are there not parts in a man's body — for example, arms, legs, 

 fingers, and toes ? Digby points out that sense does not judge 

 which is an arm, leg, finger, or toe, but that the notions corre- 

 sponding to these words are products of the understanding, 

 which, among several functions of a substance, is capable of 

 selecting one, as if the substance had no more. We are, there- 

 fore, really dealing with a fallacy of confusion. Quantity is a 

 possibility to be made distinct things by division ; whereas the 

 different limbs above named " are but a virtue to do distinct 

 things/'' Even if this were not so, sense cannot determine any 

 one part in a body ; for if it could, it would tell precisely where 

 that part begins and ends. If the part begin or end in indivi- 

 sibles, certainly sense cannot determine of them. On the other 

 hand, considering that all whereof sense is capable is divisible, 

 it continually reminds us of more potential parts than one. 



