8 BOEDER LINES OF KNOWLEDGE 



If it is true that we understand ourselves but imper- 

 fectly in health, it is more signally manifest in disease, 

 where natural actions imperfectly understood, disturbed 

 in an obscure way by half-seen causes, are creeping and 

 winding along in the dark toward their destined issue, 

 sometimes using our remedies as safe stepping-stones, 

 occasionally, it may be, stumbling over them as ob- 

 stacles. 



I propose in this lecture to show you some points of 

 contact between our ignorance and our knowledge in 

 several of the branches upon the study of which you 

 are entering. I may teach you a very little directly, 

 but I hope much more from the trains of thought I 

 shall suggest. Do not expect too much ground to be 

 covered in this rapid survey. Our task is only that of 

 sending out a few pickets under the starry flag of sci- 

 ence to the edge of that dark domain where the ensigns 

 of the obstinate rebel. Ignorance, are flying undisputed. 

 We are not making a reconnoissance in force, still less 

 advancing with the main column. But here are a few 

 roads along which we have to march together, and we 

 wish to see clearly how far our lines extend, and where 

 the enemy's outposts begin. 



Before touching the branches of knowledge that deal 

 with organization and vital functions, let us glance at 

 that science which meets you at the threshold of your 

 study, and prepares you in some measure to deal with 

 the more complex problems of the hving laboratory. 



