PRESIDENT NEWCOMB. 19 



as an instance of this the laws of the celestial motions. When 

 Kepler discovered that the planets moved round the sun in elipses, 

 having the sun in one focus, he found what were, for his time, 

 simple and elementary laws. They were entirely comprehensible, 

 admitting of being expressed in mathematical language. They 

 enabled hfm to predict the motions of the planets, and, so far as 

 the intellect of the time could penetrate, they could not be resolved 

 into more simple expressions. 



But when Newton appeared on the scene, he showed that these 

 and other laws could be expressed in the simple and comprehensive 

 form of gravitation of every particle of matter toward every other 

 particle with a force inversely as the square of the distance which 

 separates them. All the laws of planetary motion which had 

 before been discovered were shown to be reducible to this one 

 simple law, combined with certain facts respecting the directions 

 and velocities of the planetary motions. The most essential of 

 these facts is, that the velocities of the planets in their orbits are 

 such that these orbits, under the influence of the sun's gravitation, 

 are nearly circular. 



By this grand generalization Newton reduced the laws of the 

 celestial motions to a form so elementar}^, simple, and comprehen- 

 sive, that no -further reduction seems possible in our present state 

 of knowledge. Attempts have been made to show that gravita- 

 tion is itself the result of discoverable causes, but they appear to 

 me entirely unphilosophical, since the causes into which they would 

 resolve gravitation are more complex than gravitation itself. But 

 for our present purpose it is not necessary to concern ourselves 

 whether gravitation may arise from some more subtile principle, as 

 yet undiscovered. The point which I wish you to grasp is the 

 entire comprehensibility of the law, as it now stands. There is 

 no mystery surrounding it. When I say that any body left un- 

 supported will fall toward the centre of the earth until it meets 

 with the earth itself, or some other obstacle to its farther fall, you 

 know exactly what I mean, and what are the results of the law 

 which I enunciate. In a certain sense we might say that the laws 

 of nature are simply general facts, distinguished from special facts 

 by their dependence upon certain antecedent conditions. Consid- 

 ered as such, there can never be any doubt as to their meaning or 

 results. There is no profound philosophy involved in their action 



