THE BELFAST ADDRESS. 141 



2. Nothing happens by chance ; every occurrence has 

 its cause, from which it follows by necessity. 3. The 

 only existing things are the atoms and empty spase ; 

 all else is mere opinion. 4. The atoms are infinite in 

 number and infinitely various in form ; they strike 

 together, and the lateral motions and whirlings which 

 thus arise are the beginnings of worlds. 5. The 

 varieties of all things depend upon the varieties of their 

 atoms, in number, size, and aggregation. 6. The soul 

 consists of fine, smooth, round atoms, like those of fire. 

 These are the most mobile of all : they interpenetrate 

 the whole body, and in their motions the phenomena of 

 life arise. 



The first five propositions are a fair general state- 

 ment of the atomic philosophy, as now held. As regards 

 the sixth, Democritus made his finer atoms do duty for 

 the nervous system, whose functions were then unknown. 

 The atoms of Democritus are individually without 

 sensation ; they combine in obedience to mechanical 

 laws ; and not only organic forms, but the phenomena 

 of sensation and thought, are the result of their com- 

 bination. 



That great enigma, ' the exquisite adaptation of one 

 part of an organism to another part, and to the condi- 

 tions of life,' more especially the construction of the 

 human body, Democritus made no attempt to solve. 

 Empedocles, a man of more fiery and poetic nature, in- 

 troduced the notion of love and hate among the atoms, 

 to account for their combination and separation ; and 

 bolder than Democritus, he struck in with the pene- 

 trating thought, linked, however, with some wild 

 speculation, that it lay in the very nature of those 

 combinations which were suited to their ends (in other 

 words, in harmony with their environment) to maintain 

 themselves, while unfit combinations, having no proper 



