INFLUENCE ON RECENT SCIENCE 73 



when its pendulum has once been jogged, the panorama 

 of cosmical history unrolls itself inexorably. Thus 

 the universe becomes a sort of machine whose parts are 

 mechanically driven, not by some external motive force, 

 but by the mutual reactions of its parts, and so destined 

 in time to run down when this internal and available 

 energy shall have exhausted itself. And when we 

 speak of the universe, all that part of it designated 

 as living bodies and vital forces is to be included, be- 

 cause of the belief that they also can be considered as 

 ponderable masses subject to physical and chemical 

 forces. 



As an original hypothesis the work of Lucretius is 

 of no consequence. In fact his atomic theory was 

 taken almost entirely from Democritus, and it was 

 rather by the vision of the poet than by the logical 

 analysis of the man of science that he developed these 

 ideas into a picture of the nature of our world. His 

 theory was, in brief, that the universe contained in an 

 otherwise empty space an indefinite number of indivis- 

 ible and immeasurably small particles, called atoms, 

 which differed only in size, position, and shape. These 

 atoms were indestructible and by their combination 

 and separation formed all natural bodies. The motion 

 of the atoms did not arise from external forces but 

 was an inherent property of their nature. With a com- 

 mon impulse, they all moved toward the center of the 

 universe, but in addition they possessed an individual 



