THE BEGINNINGS OF LIFE. 15 



itself indestructible, then, of course, it must follow as 

 an a priori necessity that forces, or the attributes of 

 matter, are also indestructible 1 . As Professor Faraday 

 expresses it 2 , c a particle of oxygen is ever a particle 

 of oxygen nothing can in the least wear it. If it 

 enter into combination and disappear as oxygen if 

 it pass through a thousand combinations, animal, 

 vegetable, and mineral if it lie hid for a thousand 

 years, and then be evolved, it is oxygen with its first 

 qualities. Neither more nor less. It has all its original 

 force, and only that ; the amount of force which it dis- 

 engaged when hiding itself has again to be employed 



in a reverse direction when it is set at liberty 



Just as the chemist owes all the perfection of his ex- 

 periments to his dependence on the certainty of gravita- 

 tion applied by the balance, so may the physical philo- 

 sopher expect to find the greatest security and the 

 utmost aid in the principle of the conservation of force. 



1 Those who wish to follow this subject further, and to understand 

 what are its ultimate implications, cannot do better than read chapters 

 vi.-ix. of Mr. Herbert Spencer's ' First Principles.' They will then see 

 that 'persistence of force ' is really the most ultimate notion, on which the 

 doctrine of the ' indestructibility of matter ' as well as that of the 

 ' continuity of motion ' are alike dependent. He says : ' By the Per- 

 sistence of Force, we really mean the persistence of some power which 

 transcends our knowledge and conception. The manifestations either 

 as occurring in ourselves or outside of us do not persist ; but that 

 which persists is the Unknown Cause of these manifestations. In other 

 words, asserting the persistence of force is but another mode of asserting 

 an Unconditional Reality, without beginning or end.' p. 255, ist edit. 



2 ' Researches in Chemistry,' pp. 454, 459. 



