30 NATURAL HISTORY 



is the study of Geometry in material forms it is the 

 discovery of truth amid a thousand sources of error. 

 The consciousness of being able in such investiga- 

 tions to walk on to truth without failure, in spite of 

 all disturbing causes, is one of the most essential 

 requisites to encourage the student, and prepare his 

 mind for original investigations, and the source of 

 the highest pleasure to those possessing it. 



I have dwelt at length on this one sign of the 

 mineral language, because its relation to intellect 

 has appeared in all the progress of this science. It 

 has elicited more thought, its discovery is a greater 

 triumph of mind, and it still taxes the higher intel- 

 lectual powers more than all other characteristics of 

 the mineral kingdom combined. Yet they, obvious 

 as they are, have their use they are the easy part 

 which is first learned ; but when carefully studied, 

 as by some of the old mineralogists, like Werner, 

 they are wonderful in the accuracy of their results. 

 The more important are : Lustre, with all its various 

 play of light and degree of intensify Color, with all 

 its possible hues the Degree of Transparency Re- 

 fraction and Phosphorescence Electricity and Mag- 



