292 
from distance A to distance B, a potency of acceleration dis- 
appears. But it is replaced at once by an equal potency of 
retardation, when the same distance is traversed the opposite 
way. Now Force is equally Force, whether it accelerates or 
retards. Thus, when the distance varies, the entire Potential 
Energy is really unchanged, and one part of it simply changes 
its name or direction, being the same in amount as before. On 
the other hand, the motion or Kinetic Energy varies every 
moment. The sum of both, or the motion plus the Potential 
Energies, must therefore vary just as much as the motions 
themselves. 
Fallacy the fourth. The doctrine not only confounds motions 
with forces, and actual motions with forces merely possible and 
conceivable, not actual, excluding one half of the real potencies 
themselves. It also involves a further defect, as fatal as the 
rest. These Potencies, for the main part, are real impotencies. 
The total is made up from all the forces that would act through 
all possible changes of distance, if each pair of atoms were left 
to their own mutual action alone, to the furthest limit. With 
a purely repulsive law, this involves a finite value, but an 
infinite distance, and an infinite time. With a purely attractive 
law, a finite time and distance, but an infinite amount or total. 
In a mixed law, with repulsion dominant at small distances, 
the repulsive Potential Energy, to resist union, is also infinite. 
Now these Potencies, to become real, with a trillion atoms, 
would require the fulfilment of a trillion times a trillion con- 
tradictory and impossible conditions. But our atoms cannot 
isolate themselves. They are bound by the laws of physics, 
even if the mind of man is free, and not bound by them. A 
main part of the Potential Energies are real impotencies, be- 
cause the co-existence of the other atoms forbids the very con- 
dition on which the existence of these potencies depends. 
Fallacy the fifth. The whole doctrine assumes that the 
separate energies, which compose the grand total, are finite and 
measurable. There is, on this view, a fixed amount of Force 
or Energy, which travels from atom to atom, and changes 
its form, but still remains always the same. “ We must 
recognize the amounts as detei’minate, as necessarily producing 
such and such quantities of results, and necessarily limited to 
those quantities” (F. P., p. 203). 
Here we meet a double and fatal objection. First, if the 
total be finite and measurable, who has fixed this limit ? The 
unit of measurement is plainly arbitrary ; but the amount or 
number of these units is arbitrary also. We can plainly 
conceive it greater or less than any finite value whatever. 
