IMPORTANT TRUTHS ARE OFTEN HIDDEN ONES. 25 



supposing that what would be a deafening chorus of insect- 

 sounds exists around us on a summer's day, entirely un- 

 noticed by us, because our ear has no power to perceive 

 vibrations exceeding a certain degree of rapidity ; or, more 

 correctly speaking, below a certain degree of intensity. 

 Conversely, our loudest sounds may be inaudible to the 

 refined ears of insects. 



As we cannot create knowledge, we are obliged when 

 forming conclusions to draw them from the knowledge we 

 possess ; and the amount of that knowledge (though always 

 increasing) is limited. As wider experience also enables 

 us to discover exceptional instances and residuary quanti- 

 ties ; and these compel us to infer the existence of wider 

 laws and principles in order to include and explain them, 

 so is it likely, and indeed almost certain, that some of the 

 greatest truths remain still unknown, and will be dis- 

 covered. In this way some of the most important truths 

 have remained for ages unapparent. For instance, all our 

 experience of the effect of applying heat to liquids con- 

 firmed our belief that at a particular fixed and definite 

 temperature, different for each separate liquid, every sub- 

 stance passed abruptly from the liquid to the vaporous 

 state, until Sir J. Herschel suggested, and Dr. Andrews a 

 few years ago proved, that under suitable conditions of 

 temperature and pressure, substances passed by a gradual 

 change from the liquid to the vaporous structure, through 

 an intervening series of conditions in which they could not 

 be properly called either liquids or vapours. It is evident 

 therefore, that as the amount of our experience and know- 

 ledge is still comparatively small, other great truths may 

 in a similar manner remain unknown. That which is 

 beyond reason at present may not be so in the future ; but 

 it has now no place in science for want of a basis of verified 

 truth. 



