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cause, such as the will of a Creator, and there are, I am sure, 
many who will see no absurdity in the supposition that the 
unit of force might be altered, however certain they may feel, 
from experieuce, that it has undergone no change since the 
universe was formed. Mr. Spencer, it is true, looks upon the 
hypothesis that the universe was ever formed as itself incon- 
ceivable, because it is equally inconceivable with that of the 
destructibility of matter. This view has, however, I should 
hope, been already sufficiently considered in this paper, and I 
need not go back upon it. 
33. If this principle of the persistence of force, which, 
according to Mr. Spencer, is the ultimate of ultimates, not 
only including the indestructibility of matter, the conservation 
of energy, and the equality of action and reaction, but extend- 
ing to all circumstances, historical, moral, and social — if, I say, 
this principle be not an axiom (as I hope has been shown), 
the great argument of that writer against belief in a personal 
Creator of the universe falls to the ground. Hence the vast 
importance of carefully examining into the alleged axiomatic 
character of the principle. The foregoing considerations have 
reference chiefly to force in the ordinary sense of the word, 
i.e. dynamical force ; partly because it is the kind of force on 
which I have bestowed the greatest amount of thought, but 
chiefly because all that the author says about historical, moral, 
and social forces is professedly deducible from the dynamical 
principle ( First Principles , p. 429, edit. 1875), and therefore 
must stand or fall with it. I am quite prepared to have many 
defects, and even errors, pointed out in what I have said. I 
can sincerely assert that I have ventured upon the foregoing 
remarks with the utmost diffidence, at the kind request of our 
Secretary, and shall thankfully accept any corrections or 
criticisms that may be made upon them. But whatever errors 
I may have committed in detail, I think the main conclusion 
for which I contend is still made out, namely, that the recently 
established principles (if they may be looked upon as esta- 
blished) of conservation of energy, persistence of force, and 
others akin to them, are unwarrantably and without reason 
pressed into the service of unbelief by men of science. The 
principle that kinetic and potential energy are complementary, 
which is one form of the persistence of force, can go no farther 
than to show that the algebraic sum of the forces of the 
universe has not been hiown to change. The inference that it 
cannot change is quite illogical, and it is on this unwarrant- 
able inference that the whole structure of scientific unbelief 
rests. 
