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[August, 
CORRESPONDENCE. 
%* The Editor does not hold himself responsible for statements of fadts or 
opinions expressed in Correspondence, or in Articles bearing the signature 
of their respective authors. 
ON A POINT RELATING TO BRAIN DYNAMICS. 
To the Editor of The Journal of Science. 
Sir, — The following letter “ On a Point relating to Brain Dyna- 
mics ” (referred to by me in the article on “ Natural Science and 
Morality,” in your last number) might possibly have some inte- 
rest as a mode of reconciling Free Will v. Necessity , said to be 
similar to that proposed by the late Prof. Clifford in an oral 
ledlure, at St. George’s Hall, on “ Body and Mind.” I am not 
aware if this ledture has been published, and the views in the 
subjoined letter were of course arrived at quite independently. — 
I am, &c., 
S. Tolver Preston. 
From “Nature ” May 13, 1880. 
Any attempt to grapple with the dodtrine of Free Will v. 
Necessity on the old lines would probably (and deservedly so) 
not attradl much attention. The objedf of this paper is to place 
a consideration of extreme simplicity under critical notice, which 
would seem to be capable of affording a key to the complete 
reconciliation of the divergent views on a common basis ; and 
since the matter to be dealt with will be stridlly within the 
domain of natural science, a clear analysis will be rendered 
possible. 
It is well known that the only attempt to harmonise the doc- 
trine of Free Will with the principle of the Conservation of 
Energy consists in supposing that living creatures have a power, 
by the mere exercise of their “ will,” of defledting particles of 
matter within their bodies from their natural paths, without 
thereby altering the total energy of the particles.* This, there- 
* The necessity for this special assumption, in order to prevent Free Will 
from coming into direct collision with the principle of the Conservation of 
