62 FRAGMENTS OF SCIENCE. 



be an attraction. Newton pondered all these things. He 

 had a great power of pondering. He could look into the 

 darkest subject until it became entirely luminous. How 

 this light arises we cannot explain ; but, as a matter of 

 fact, it does arise. Let me remark here, that this power of 

 pondering facts is one with which the ancients could be 

 but imperfectly acquainted. They found the uncontrolled 

 exercise of the imagination too pleasant to expend much 

 time in gathering and brooding over facts. Hence it is that 

 when those whose education has been derived from the 

 ancients speak of " the reason of man," they are apt to 

 omit from their conception of reason one of its greatest 

 powers. Well, Newton slowly marshalled his thoughts, or 

 rather they came to him while he " intended his mind," 

 risino; one after another like a series of intellectual births 

 out of chaos. He made this idea of attraction his own. 

 But to apply the idea to the solar system, it was necessary 

 to know the magnitude of the attraction and the law of its 

 variation with the distance. His conceptions first of all 

 passed from the action of the earth as a whole, to that of 

 its constituents particles, the integration of which composes 

 the whole. And persistent thought brought more and 

 more clearly out the final divination, that every particle of 

 matter attracts every other particle by a force which varies 

 inversely as the square of the distance between the par- 

 ticles. This is Newton's celebrated law of inverse squares. 

 Here we have the flower and outcome of his induction ; and 

 how to verify it, or to disprove it, was the next question. 

 The first step of Newton in this direction was to prove, 

 mathematically, that if this law of attraction be the true 

 one ; if the earth be constituted of particles which obey 

 (his law; then the action of a sphere equal to the earth in 

 size on a body outside of it, is the same as that which 

 would be exerted if the whole mass of the sphere were 

 contracted to a point at its centre. Practically speaking, 



