362 FRAGMENTS OF SVIENCti. 
his time men had occupied themselves with the problem of 
the solar system. Kepler had deduced, from a vast mass 
of observations, those general expressions of planetary 
motion known as " Kepler's laws." It had been observed 
that a magnet attracts iron; and by one of those flashes of 
inspiration which reveal to the human mind the vast in 
the minute, the general in the particular, it had been 
inferred, that the force by which bodies fall to the earth 
might also be an attraction. Newton pondered all these 
things. He looked, as was his wont, into the darkness 
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 kind of pondering is a proc- 
ess with which the ancients could have been but imper- 
fectly acquainted. They, for the most part, found the 
exercise of fantasy more pleasant than careful observation, 
and subsequent 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 most im- 
portant factors. Well, Newton slowly marshaled his 
thoughts, or rather they came to him while he " intended 
his mind," rising 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 varia- 
tion with the distance. His conceptions first of all passed 
from the action of the earth as a whole, to that of its con- 
stituent particles. And persistent thought brought more 
and more clearly out the final conclusion, that every par- 
ticle of matter attracts every other particle with a force 
varying inversely as the square of the distance between the 
particles. 
Here we have the flower and outcome of Newton's in- 
duction; and how to verify it, or to disprove it, was the 
next question. The first step of the philosopher 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 this 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 center. Prac- 
tically speaking, then, the center of the earth is the point 
