HISTORY OF THE ATOMIC THEORY. 289 



These remarks are called forth by the peculiar progress of 

 some of the early opinions and the difficulties encountered 

 when experiment began. We may arrange the numerous 

 theories spoken of in the following manner, seeking the 

 spirit or fundamental idea of each. 



First we have one matter out of which all the others were 

 made. This in early times was real substantial matter, as water 

 and earth ; afterwards a dynamical water or earth, or a natural 

 force corresponding to them or underlying them. Then the 

 four elements were made the origin of all things ; but conver- 

 tible. These theories, although under some aspects going 

 under various heads, may be conveniently put under one 

 and be called the Allhylic. (aXXoc and iJXi?, interchangeable 

 elements.) 



The next, although allied, claims for itself a separate 

 place. When there is recognised a universal matter, a prima 

 materia from which all things are made, and which itself 

 has no substantial qualities, but is capable of assuming 

 all, it may be called the prothylic theory, (tt^wtij v\r\, first 

 element as it was called.) 



When matter is made up of indivisible particles, the name 

 atomic is already appropriately given, (a and to/xoc, uncut.) 



When particles are infinitely divisible, it may be useful to 

 call this theory the dia-tomic. (^la and tojuoc cut through.) 



When we find the original matter to be a force only, whether 

 represented by a number, a point, a line, a geometrical figure, 

 or a more abstract idea, this is the dynamical theory. 



When there are neither forces nor atoms, nor distinct 

 elements, nor universal and insuperable laws, nor a sub- 

 stratum of primary matter, the mystic theory seems an appro- 

 priate name. 



In the early atomic theories, the only difference recognised 

 in atoms is their shape. These theories are mechanical. 

 Now we recognise many original differences forming elements. 

 This is a polyhylic atomic theory. 



2P 



