Principle of the Conservation of Energy. 63 



action of the forces of nature is to liberate themselves from inti- 

 mate connexion with matter ; and whenever we make them act 

 in opposition to this law, we see that we only prepare for a state 

 that will afterwards be destroyed : we can hinder the straight and 

 direct action of the forces to some extent, but we cannot stop it. 

 And as this is a general law of nature for the action of the elec- 

 trical and chemical, the magnetic and mechanical forces, there is 

 certainly no reason to believe that it should not be a general law 

 for all the forces of nature. 



If it be now called to mind that intellectual life commenced 

 with the creation of human beings ; 



That human beings did not arise, and therefore must be sup- 

 posed to be unable to have lived on the earth before it was suffi- 

 ciently cultivated by numerous animals ; 



That a great number of these could not live until numerous 

 other animals, living solely on vegetables, had prepared the earth 

 for them ; 



That these animals could not subsist until plants had previ- 

 ously cultivated the ground ; 



That many of the plants certainly could not live before other 

 plants had prepared the ground for them ; 



That no plants at all would have been able to live had not the 

 ground been sufficiently prepared and cultivated by the action of 

 the chemical forces ; and 



That this action could not possibly have taken place had not 

 the chemical forces been called into existence by the energy ge- 

 nerated by the original power of gravity ; — if, I say, we call this 

 to mind, I think it cannot fail to strike us, not only that it was 

 necessary for the ground to be thus prepared and cultivated 

 before human beings could live on the earth, but also that it was 

 in like manner necessary that the forces themselves should be 

 prepared and cultivated before they could take on the form of 

 intellectual life. 



But if so, I think it must be satisfactory to us to see that, 

 according to the principle of the perpetuity of energy, we arrive 

 at the conclusion that the intelligent life of man must be an in- 

 telligent life for ever ! 



Gentlemen, — After asking for a place in your Journal of 

 Science for this extract or outline of my different memoirs on the 

 forces, I beg leave to trouble you with the question whether, after 

 what I have stated in this extract, you would like to have for 

 your Journal a copy of my first memoir translated into English, 

 as such would enable your readers to judge more fully of my 

 position relatively to the new principle at the time (1843) when 

 I wrote my " Theses concerning Force," and as it would also 



