358 FRAGMENTS OF SCIENCE. 



Nature as an organic whole, as a body each of whose 

 members sympathizes with the rest, changing, it is true, 

 from ages to ages, but without one real break of continuity, 

 or a single interruption of the fixed relations of cause and 

 effect. 



The system of things which we call Nature is, however, 

 too vast and various to be studied first-hand by any single 

 mind. As knowledge extends there is always a tendency 

 to subdivide the field of investigation, its various parts be- 

 ing taken up by different individuals, and thus receiving a 

 greater amount of attention than could possibly be bestowed 

 on them if each investigator aimed at the mastery of the 

 whole. East, west, north, and south, the human mind 

 pushes its conquests ; but the centripetal form in which 

 knowledge, as a whole, advances, spreading ever wider on 

 all sides, is due in reality to the exertions of individuals, 

 each of whom directs his efforts, more or less, along a single 

 line. Accepting, in many respects, his culture from his 

 fellow-men, taking it from spoken words and from written 

 books, in some one direction, the student of Nature must 

 actually touch his work. He may otherwise be a dis- 

 tributor of knowledge, but not a creator, and fails to attain 

 that vitality of thought and correctness of judgment which 

 direct and habitual contact with natural truth can alone 

 impart. 



One large department of the system of Nature which 

 forms the chief subject of my own studies, and to which it 

 is my duty to call your attention this evening, is that of 

 physics, or natural philosophy. This term is large enough 

 to cover the study of Nature generally, but it is usually 

 restricted to a department which, perhaps, lies closer to 

 our perceptions than any other. It deals with the phe- 

 nomena and laws of light and heat — with the phenomena 

 and laws of magnetism and electricity — with those of 

 sound — with the pressures ;md motions of liquids and 



