OF NATURAL PHILOSOPHY. 49 



slowness, and in such cases it is often of the highest 

 practical importance to accelerate them. The 

 bleaching of linen, for instance, performed in the 

 natural way by exposure to sun, rain, and wind, 

 requires many weeks or even months for its com- 

 pletion ; whereas, by the simple immersion of the 

 cloth in a liquid, chemically prepared, the same 

 effect is produced in a few hours. The whole circle 

 of the arts, indeed, is nothing but one continued 

 comment upon this head of our subject. The 

 instances above given are selected, not on account 

 of their superior importance, but for the simplicity 

 and directness of application of the principles on 

 which they depend, to the objects intended to be 

 attained. 



(4-2.) But so constituted is the mind of man, that 

 his views enlarge, and his desires and wants in- 

 crease, in the full proportion of the facilities afforded 

 to their gratification, and, indeed, with augmented 

 rapidity, so that no sooner has the successful exer- 

 cise of his powers accomplished any considerable 

 simplification or improvement of processes subser- 

 vient to his use or comfort, than his faculties are 

 again on the stretch to extend the limits of his 

 newly acquired power ; and having once experienced 

 the advantages which are to be gathered by availing 

 himself of some of the powers of nature to accom- 

 plish his ends, he is led thenceforward to regard 

 them all as a treasure placed at his disposal, if he 

 have only the art, the industry, or the good fortune, 

 to penetrate those recesses which conceal them from 

 immediate view. Having once learned to look on 

 knowledge as power, and to avail himself of it as 



