LUCRETIUS 21 



Lucretius has given us the most consistent and 

 systematic atomic theory of ancient times, and it 

 will repay us to look at its main features. 



Plunging at once in medias reSy the poet explains 

 the purpose of his poem. " I will unfold the 

 atoms whence Nature forms, and increases, and 

 feeds all things that are, and into which she dis- 

 solves them again after their destruction." 



The sun, the moon, he says, are moved not by 

 the caprices of the gods, but by natural inevitable 

 mechanical laws, and, indeed, by natural inevitable 

 mechanical laws all things are made and moved. 

 " It is absolutely decreed," he asserts, " what each 

 thing can do, and what it cannot do, according to 

 the conditions of Nature." 



" Unde refert nobis victor quid possit oriri 

 Quid nequeat, finita potestas denique cuique 

 Quanam sit ratione atque alte terminus haerens. 

 Quare religio pedibus subjecta vicissim 

 Opteritur, nos exaequat victoria coelo." 



He holds that the universe consists of atoms 

 and a void ; and, given atoms and a void, he is 

 prepared to show how the universe came into 

 being. He argues that matter is built up of atoms, 

 and that the atoms are impenetrable, indivisible, and 

 indestructible — " solida pollentia simplicitate." If 

 destructible, he says, there would not be the uni- 

 formity in objects which now obtains ; for as the 



