CLASSICAL AND NEW MECHANICS 143 



tached to this entity, but whether it be called an atom, 

 an ether, a vortex, electricity, or energy, its function 

 is the same. While there is little difference in the 

 nature of this entity or substance, yet there are two 

 diametrically opposite ways of considering its space 

 attributes which give rise to two irreconcilable schools 

 of thought. One of these considers the primordial sub- 

 stance to be discontinuous with its parts separated by 

 vacuous spaces, and the other school just as con- 

 fidently assumes that there can be no empty spaces, 

 and that all space is therefore continuous. Arguments 

 for and against these two views have been unceasing 

 and are likely to continue, so long as hypothetical 

 methods remain in vogue. The problem is quite in- 

 capable of solution because the postulate of continuity 

 or discontinuity is a matter of conviction rather than 

 of reason. The fact is, we believe one or the other to 

 be true and that is the end of it. In such discussions 

 where a postulate is beyond our powers of verifica- 

 tion by experience, each contestant chooses his starting- 

 point, and this once chosen, his argument in favor of 

 it is as sound as that of his opponents. And the truth 

 of this assertion is evident, because from these dia- 

 metrically opposite postulates, conclusions which are 

 quite identical are deduced by equally logical argu- 

 ments; witness the controversy between the atomists 

 and the Cartesians which see-saws through all scientific 

 theory and is as far from settlement to-day as it was 



