10 PRINCIPLES OF MOTION. 



Plato, Aristotle, and the Pythagoreans, supposed that 

 throughout all nature an active principle was diffused, 

 upon which depended all the properties exhibited by 

 matter. This is the same as the " plastic nature " of 

 Cudworth,* the "intellectual and artificial fire" of 

 Bishop Berkeley ; f and to these all modes of motion 

 were referred. Sir Isaac Newton also regards the 



reduced to rest, and after it hath continued at rest, so long as other 

 bodies do not put it out of that state, may by external agents be 

 set a moving again; I, who am not wont to think a man the worse 

 naturalist for not being an atheist, shall not scruple to say with an 

 eminent philosopher of old, whom I find to have proposed among 

 the Greeks that opinion (for the main) that the excellent Des Cartes 

 has revived amongst us, that the origin of motion in matter is 

 from God; and not only so, but that thinking it very unfit to be 

 believed, that matter barely put into motion, and then left to 

 itself, should casually constitute this beautiful and orderly world ; 

 I think also further, that the wise Author of things did, by estab- 

 lishing the laws of motion among bodies, and by guiding the first 

 motions of the small parts of matter, bring them to convene after 

 the manner requisite to compose the world ; and especially did 

 contrive those curious and elaborate engines, the bodies of living 

 creatures, endowing most of them with the power of propagating 

 their species." Considerations and Experiments touching the Origin 

 of Forms and Qualities: Boyle's Works, vol. ii. p. 460. Edin- 

 burgh. 1744. 



* Cudworth's Intellectual System. 



f " According to the Pythagoreans and Platonists, there is a 

 life infused throughout all things ... an intellectual and 

 artificial fire an inward principle, animal spirit, or natural life, 

 producing or forming within, as art doth without regulating, 

 moderating, and reconciling the various motions, qualities, and 

 parts of the mundane system. By virtue of this life, the great 

 masses are held together in their ordinary courses, as well as the 

 minutest particles governed in their natural motions, according to 

 the several laws of attraction, gravity, electricity, magnetism, and 

 the rest. It is this gives instincts, teaches the spider her web, and 

 the bee her honey ; this it is that directs the roots of plants to 

 draw forth juice from the earth, and the leaves and the cortical 

 vessels to separate and attract such particles of air and elemen- 

 tary fire as suit their respective natures." Bishop Berkeley, Siris^ 

 No. 277. 



