20 ADDRESS OP 



or expression any more than there is in such statements as that all 

 unsupported bodies fall toward the centre of the earth ; that gun- 

 powder, when touched by fire, suddenly changes to an incandescent 

 gas ; that water, at ordinary pressure, changes to steam at a 

 temperature of 212. 



Now, scientific investigators are earnestly endeavoring, each in 

 his own sphere, to do for the whole of nature what Newton did for 

 the laws of planetary motion, to find and announce the elementary 

 principles which connect all the links of the endless chain which 

 symbolizes her course. The student of chemistry cannot doubt 

 that the innumerable properties of the various compounds which 

 he studies arise from the play of certain attractive and repulsive 

 forces among the elementary molecules of the matter of which 

 these compounds are formed. Could he only learn the law ac- 

 cording to which these forces act, chemistry might become very 

 largely a deductive science, and the properties of compounds 

 might be predicted in advance, as the astronomer predicts the 

 conjunctions of the planets. The idea now entertained by those 

 who see farthest in this direction is that all the physical properties 

 of matter depend upon and may be reduced to certain attractive 

 and repulsive forces acting among the ultimate atoms of which 

 matter is composed. 



It may also be supposed that all the operations of the vital 

 organism, both in men and animals, depend, in the same way, 

 upon molecular forces among the atoms which make up the organ- 

 ism. The operation of forces unknown to chemistry must, indeed, 

 be presupposed, but there is no reason to suppose that these 

 forces are less simple than chemical ones. Some would even go 

 so far as to explain the facts of consciousness in this way. The 

 philosophy of this explanation belongs, however, to another de- 

 partment of thought that of scientific materialism into which 

 we cannot at present enter. 



The most startling attempts, in the direction I have indicated, 

 are those which are designed to show that those wonderful adap- 

 tations which we see in the structure of living animals, and which 

 in former times were attributed to design, are really the result of 

 natural laws, acting with the same disregard to consequences which 

 we see in the falling rock. The philosophy of Darwinism, and the 

 theory of evolution, will be at once brought to your mind as form- 



