FACULTIES OF THE MIND. 253 



habit. The standard of temperature may be altered a few 

 degrees, provided the change be slowly brought about. 

 If it is attempted rapidly, a diseased state of the system, in 

 general, is the consequence. In some cases, the sensibility 

 of the nerves is, to a certain extent, destroyed by the 

 change, so that the exposed parts cease to experience those 

 painful impressions which, under other circumstances, 

 would have been produced. 



Man is the only being on this globe who, in the gratifi- 

 cation of this desire, kindles a fire wherewith to warm 

 himself. He makes use of friction or percussion to ex-i 

 cite the heat, in the first instance, and employs vegetables, 

 or bituminous minerals, to increase and continue it. It 

 is impossible to ascertain, whether this was originally the 

 discovery of an individual, and subsequently communicated 

 by example or tradition, or whether it be really a cha- 

 racter of this active power as it exists in man. It is at 

 least certain, that the use of artificial heat is coeval and co- 

 existent with our race. The monkey may approach the 

 fire which the savages have left, and warm himself at its, 

 glowing embers, but he is never prompted to secure a con- 

 tinuance of the comfort, by the addition of fresh fuel, or 

 by setting fire to combustible matter in another situation. 



2. Clothing. Many animals are produced at their 

 birth, in such circumstances, that they stand in no need of 

 any other clothing than the skin, an4 its natural appen- 

 dices, and continue through life independent of the protec- 

 tion of foreign bodies. Such animals are, of course, un- 

 provided with this instinctive principle. But there are 

 other animals which, during a part or the whole of life> 

 stand in need of an artificial covering for their protection. 



Of those which cover themselves only during a certain 

 part of life, there are some which derive the materials of 

 their habitation from their own body, as the silk-worm, 



