24 GENERAL VIEW AND BASIS OF SCIENTIFIC RESEARCH. 



to devise means of isolating and distinguishing them. It 

 was not because those substances were inaccessible that 

 they were not previously discovered (for men had lived 

 through ages in the closest contact with them), but for want 

 of scientific knowledge, and of suitable and sufficiently re- 

 fined methods of manipulation. In other cases where such 

 knowledge and refined methods were not necessary, as in- 

 distinguishing diamonds, gold, silver, and various other 

 bodies, the discoveries were made so long ago, that the 

 records of them, if there were any, are lost. The discovery 

 of gold required far less knowledge and intelligence than 

 that of the vastly more abundant substances oxygen and 

 nitrogen, because it was a glittering solid, and its properties 

 more conspicuous. Even at the present time all our 

 methods and appliances are extremely crude, when com- 

 pared with the minuteness and complexity of molecular 

 phenomena to be discovered. The most important truths 

 are usually the least obvious. Many of the greatest truths 

 remaining unknown can probably be discovered only by 

 means of exhaustive researches which disclose exceptional 

 instances, or of extreme refinements in science, which will 

 enable us to detect and examine excessively minute 

 residuary quantities of forces and substances ; and the 

 probable reason why we have not yet been able to discover 

 an experimental connection between gravity and the 

 various physical forces, is because of the extreme feeble- 

 ness of the former force in comparison with the strength 

 of the latter. For equal masses of matter, the proportion- 

 ate strength has been estimated to be a mere fraction of 

 1 to 1,000 millions. 1 



The extremely limited extent of our faculties also keeps 

 us in ignorance of many things. There is good reason for 



1 The Unseen Universe, 5th edit., p. 145. 



