2\ Life and Matter [chap. h. 



directing agency, whereas really it has 

 nothing to say on these topics ; it relates to 

 amount alone. Philosophers have been far 

 too apt to jump to the conclusion that 

 because energy is constant, therefore no 

 guidance is possible, so that all psycho- 

 logical or other interference is precluded. 

 Physicists, however, know better ; though 

 unfortunately Tyndall, in some papers on 

 Miracles and Prayer, thoughtlessly adduced 

 the conservation of energy as decisive. This 

 question of " guidance " is one of great 

 interest, and I emphasise the subject further 

 on, especially in Chapter IX. 



Conservation of Matter. 



Take next the " conservation of matter " 

 which means that in any operation, 

 mechanical, physical, or chemical, to which 

 matter can be subjected, its amount, as 

 measured by weight, remains unchanged ; so 

 that the only way to increase or diminish the 

 weight of substance inside a given enclosure, 



