SEARCHING FOR IMPOSSIBLE THINGS. 17 



destructive, and physical properties and motions which are 

 incompatible. Many statements of fact also do not admit 

 of degree ; for instance, a substance either exists or it does 

 not. According to the principles of geometry, there can- 

 not exist more than five regular solids. 



We do not create laws, nor can we command new 

 effects, except those which are in harmony with the prin- 

 ciples of nature. Scientific research or genius, therefore, 

 cannot create l new truths ; it can only discover such as 

 are in perfect accordance with the laws of matter and its 

 forces. It is essentially truthful, and cannot verify our 

 hypotheses unless they are true. 



We must, however, carefully distinguish between the 

 evidence supplied by the results of research and the 

 observations, comparisons, and conclusions to be drawn 

 from them. The former may be true, but the latter may 

 be erroneous. Truth is that which is, and no matter how 

 extraordinary truth may appear, our thought must be 

 made to agree with it. The knowledge which we acquire 

 by research in the physical and chemical sciences, 

 although it may, so far as it goes, in most cases be tho- 

 roughlv trusted as to matters of qualitative fact, is always 

 incomplete and quantitatively inexact. More always re- 

 mains to be known, and hat which is known possesses 

 only a finite degree of precision. This arises from the 

 extremely limited power of our faculties and means of 

 detection and observation, and pur present incapability 

 to appreciate absolute accuracy. As the analogies and 

 conclusions we draw from research and experience are 

 sometimes erroneous, we are frequently led by them to 

 search for things which cannot exist. Every scientific 

 investigator has his own notions of what is impossible ; 



1 I use this word in an absolute sense, viz. to form out of nothing. 



C 



