ENERGISM : THE FUNDAMENTAL PRINCIPLES OF 
DYNAMIC REALISM28 
Energy we define as the pure spontaneity of activity, while 
force is the same activity under limitation, as we meet it in our 
experience. We have to do with force and postulate energy 
only on grounds of logical necessity. Common sense revolts 
at the idea that the objects about us are not real, and the position 
above indicated is easily misrepresented as though it were main- 
tained that there is no such thing as a real being apart from the 
process in my mind which brings it into consciousness. We are 
assured of the reality and objectiveness of the stone wall because 
of the uniformity of our experiences and the conformity of the 
testimony of others. What we deny is that the reality of the 
stone wall is any greater for adding the undemonstrable idea of 
material elements in the wall. Certain forces acting with uni- 
formity in definite relations form the only basis of reality which 
psychology or physics can afford. 
Experience is a name for the changes which take place in our 
conscious selves. There may be many changes in the surrounding 
world and in our very bodies, but none of these is a part of experi- 
ence until it has made itself consciously felt. Changes in our 
brains and in the current of our physical organism otherwise may 
produce alterations in the subsequent course of consciousness; 
but only when these conscious alterations actually appear can 
they be said to have entered experience. The most careful 
analysis which physics has been able to make of the phenomena 
of the physical world has resulted in nothing more than the dis- 
covery of a great variety of forces operating in the field of our 
experience. Force is simply a name for anything that affects 
experience. Comparatively few forces are thus known directly, 
but in most cases the force is inferred from the interpretation 
of indirect effects of forces on experience. We may think of the 
rays of light impinging on the retina as forces directly affecting 
Cf, ‘^ The Passing of Scientific Materialism/’ The Monist, January, 1905, pp' 
46-84. 
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