LECTURES 



because I hold that the clearness and breadth 

 or dimness and narrowness of our ideas regarding 

 matter and force must constitute a good or a 

 bad foundation of all the knowledge we possess, 

 not only in medicine, but in every other 

 science. 



In the history of the development of scien- 

 tific knowledge, whether in mankind, nations, 

 or individuals, ideas of matter and force are 

 found to become gradually more clear and more 

 broad; and, as soon as clearer and more 

 connected ideas are obtained, they immediately 

 lead to fresh investigations ; and on this ac- 

 count, if for no other cause, it is desirable that 

 from time to time we should ask ourselves 

 what is the degree of clearness and breadth to 

 which we have attained in our ideas of matter 

 and force ? 



What are our present ideas ? Whence have 

 they come ? Whither are they going ? 



Ideas that have become too old give no new 

 lines of research, and always cause the grossest 

 misinterpretation of new facts; whilst new 

 ideas, even though far from the perfect repre- 

 sentation of the ultimate truth, yet can gradu- 

 ally be made to come nearer and nearer to that 



