FIRST PRINCIPLES 13 



back, to find himself before the weary paradox : that ultimate 

 matter is force, and ultimate force is matter. The definite 

 proportions in which "elements" combine together leaves 

 the chemist in no doubt as to the ultimate constitution of 

 matter. It consists of atoms ideally indivisible, because we 

 can conceive of nothing which can divide them although 

 both physicist and chemist are beginning to regard the 

 ' ' atom ' ' of Walton as a cluster of atoms, or sub-atoms of 

 matter, more fundamental than the elements ; similar atoms 

 unite into squads or molecules which are units of chemical 

 combination. A binary compound is a combination of x 

 molecules of one element with y molecules of another. The 

 simple numerical relations between the various elements as 

 regards their atomic weight and specific heat, which enables 

 the chemist to arrange them into several parallel series 

 according to the "periodic law," leads him to the conclusion 

 that there is only one kind of true atom variously united 

 into groups by cohesive force. If there is only one ultimate 

 indivisible atom, there must be as many kinds of cohesive 

 force as there are different "elements." "Impossible," 

 the physicist exclaims ; ' ' there is only one kind of cohesive 

 force. Either there are as many kinds of atoms as there are 

 elements, or else, as is more probable, your atom is not 

 matter at all, but a centre of force for force is the one 

 thing which you cannot think away, and the difference 

 between one element and another lies in the amount of force 

 which each centre, or atom, represents." The simplicity of 

 the positions taken up by the most profound thinkers, 

 when, after passing through abstruse and recondite pro- 

 cesses of reasoning, they try to take a steady view of the 

 ultimate constitution of things, would bring a smile to 

 the face of a Greek philosopher accustomed to more 

 generous theories. The most learned physicist becomes 

 as a little child. 



The biologist at an early stage in his career begins to 

 ask himself, What is life? As age advances he finds that 



