of thought. For motion would he destroyed by collision of finite 
atoms, which stop each other, without gradual repulsion, by their 
impenetrable extension alone. Next, in physiology, it excludes 
all forces which are functions of the time, or which begin at a 
fixed time, reach a maximum, and sink to zero at or within 
some given period. It excludes also discriminating attraction 
or repulsion, determined not by mere distance, but by relation 
to some type or model. Now these are exactly the two characters 
which life and living organic powers appear to possess. Thirdly, 
in humanity and theology, it excludes all forces which depend 
on the desires of sentient creatures, and the choice and will of 
a reasoning and moral agent, human or divine. The first of 
these three conditions is probable, but not yet proven. The 
second is both unproved and improbable. The third is not only 
unproved and improbable, but certainly and most mischievously 
untrue. 
Mr. Brooke’s paper on Force and Energy, on this higher side, 
is a total contrast to Mr. Spencer’s Principles and Dr. Tyndall’s 
address. Instead of binding nature fast in the bonds of fate, 
to the destruction of all morality and religion, lie confines 
the doctrine to physics as its only legitimate scope, and views 
it, even there, as wholly subject to the wisdom and choice of 
an almighty and omniscient Creator. But within the limit of 
Physics the contrast ceases, and is replaced by a strange re- 
semblance. Both Mr. Spencer and Mr. Brooke affirm the 
doctrine, almost with equal confidence, and both alike, without 
consciousness of the inconsistency, reject and set aside the 
conditions essential to its truth. My own theory of Matter and 
Ether, published twelve years ago, satisfies those conditions. I 
still believe it, if not true, to be a close approach to the truth, 
and a help to its future discovery, and expect that the real laws 
of nature, if different from those I have suggested, will equally 
fulfil these main conditions. But Mr. Spencer, who takes the 
doctrine for a necessary truth, and Mr. Brooke, who thinks its 
truth indisputable, from the inexorable logic of facts, and clear 
as the sun at noonday, deny four main premises, required for 
an intelligent acceptance of the doctrine, and thus reduce it to 
ashes with their own hands. 
The Conservation of Motion, or the use of the Potential 
Function, as a dynamical formula, applies to any system, great 
or small, where all the forces are functions of the mutual dis- 
tances of the atoms alone. To make it the known law of the 
universe, two things must be proved and known, — that such 
atomic laws do exist, and that no forces or powers operate 
