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352 ‘ LAPLACE. 
they could explain every thing mechanically according 
to the simple evolutions of atoms, excepted gravity from 
their speculations. 
Descartes attempted what Leucippus, Democritus, Epi- 
curus, and their followers thought to be impossible. 
He made the fall of terrestrial bodies depend upon the 
action of a vortex of very subtle matter circulating 
around the earth. ‘The real improvements which the 
illustrious Huyghens applied to the ingenious conception 
of our countryman were far, however, from imparting to 
it clearness and precision, those characteristic attributes 
of truth. 
Those persons form a very imperfect estimate of the 
meaning of one of the greatest questions which has occu- 
pied the attention of modern inquirers, who regard New- 
ton as having issued victorious from a struggle in which 
his two immortal predecessors had failed. Newton did 
not discover the cause of gravity any more than Galileo 
did. Two bodies placed in juxtaposition approach each 
other. Newton does not inquire into the nature of the 
force which produces this effect. ‘The force exists, he 
designates it by the term attraction; but, at the same 
time, he warns the reader that the term as thus used by 
him does not imply any definite idea of the physical 
process by which gravity is brought into existence and 
operates. 
The force of attraction being once admitted as a fact, 
Newton studies it in all terrestrial phenomena, in the 
revolutions of the moon, the planets, satellites, and com- 
ets; and, as we have already stated, he deduced from 
this incomparable study the simple, universal, mathemati- 
cal characteristics of the forces which preside over the 
movements of all the bodies of which our solar system 
is composed. 
