232 PRODUCTIONS 



of it is a species of fraudulent idleness ; if we go 

 on with an inquiry in the proper manner, we are 

 always sure to come to it; but if we begin with 

 it or resort to it before the proper time, our in- 

 quiry is at an end, and our ignorance of that 

 subject is sealed. 



Rocks are proverbially associated with barren- 

 ness, though there is no rock but which, if left at 

 rest and watered, will produce its plants nay, a 

 succession of races ; and if the climate were favour- 

 able, and we could wait long enough, there is not 

 the least doubt that we could water a rock till it 

 became so fertile on the surface that we could sow 

 it with grain, or plant it with vegetables. Peb- 

 bles in a brawling stream, or rolled on the beach 

 by the waves, are unproductive things certainly ; 

 and not merely that, for they wear one another ; 

 but examine the very same kind of pebbles in a 

 shallow standing pool, or on a part of the beach 

 where they are left at rest, and you will find that 

 they have their plants and their animals. The 

 mountain rocks, even in the coldest places, are 

 covered with lichens, some of which are of value 

 in the arts, and others as articles of food. Many 

 dyeing materials are obtained from those curious 

 productions, some of which are in themselves not 

 easily distinguished from the rocks on which they 

 grow. 



The common people in the northern countries 

 have long been in the habit of dyeing their stuffs 

 with these substances ; and in their hands the 

 colours that are produced are very durable, though 

 not very brilliant. The orchal, or French rock- 

 moss, (Lichen parellus, of Linnaeus,) which forms 

 a very white, rough, and warty crust on the 



