x Mechanism of the Nervous System. 187 



that the transformation of an infinitesimally small 

 quantity of nervous energy is effected in the brain, by 

 the immediate act of the Will, from the stored or 

 static form (analogous to electricity in a Leyden jar), 

 into the kinetic or current form (analogous to 

 electricity running along a wire) ; this determines 

 the flow, from the brain down to the muscle, of a 

 nervous current ; which current, however, is almost 

 exclusively supplied, not from the brain, but by the 

 transformation, from the static into the current form, 

 of the energy that was stored in the nerve itself ; and 

 this in its turn determines the transformation of the 

 stored energy of the muscles themselves into working 

 energy. Here are three successive transformations 

 of energy, whereof the first and the second each 

 determines that which succeeds it, and is probably 

 almost infinitesimally smaller than that which it 

 determines. This presents an obvious analogy to 

 the case already mentioned, of the engineer, with a 

 turn of his hand, starting a small steam-engine which 

 starts a large one. The number of links in the chain 

 of causation may be greater than this, but it appears 

 scarcely possible that they can be very many. It is 

 at least conceivable that in the original determination 

 within the brain, the Will may be free, in that absolute 

 sense in which Delboeuf, in the passage first quoted, 

 defines Freedom, either to effect or not to effect that 

 transformation of energy on which depends the 

 sending downwards of the nervous current that sets 

 the muscle in action ; for we cannot doubt that energy 



