37 ° 
Past Changes in the Universe. [July, 
analogy in the stellar masses and the media in which they 
are immersed moving under the same dynamical principles. 
Moreover, the kinetic theory has been mathematically proved 
(when a large number of masses are concerned) to produce 
a system of order and symmetry (or mean similarity of the 
conditions in all parts of the system) which is rigidly and 
automatically maintained by a process of self-correCtion 
under dynamical principles — a self-aCting adjustment of the 
motions continually taking place, whereby a system of har- 
mony and order is maintained everywhere, a perfect state 
of mobile equilibrium existing in all parts. 
Those who regard the physical causation of the past in 
the light of the physical causation of the present, or who 
look upon the principle of the conservation of energy as a 
truth as necessary in the past as in the present (or who look 
upon physical truths as independent of time), are bound to 
believe that some process of recurrence must exist, whereby 
useful change and activity are continued in the Universe, 
and the purposeless end of a changeless chaos prevented ; 
and that we should seek for the explanation of this, not so 
much with the view to prove the faCd thereby, but rather as 
a satisfaction or confirmation of a faCt we already had 
logical grounds for believing to exist. As we happen to 
have given considerable time and thought to the problem of 
gravitation on the basis of Le Sage’s fundamental idea, we 
have considered ourselves justified in calling attention to 
the important consequences and modified views regarding 
natural phenomena that the acceptance of the physical 
theory of gravitation entails. 
The phenomena of Nature would thus consist in cyclical 
processes involving transferences of motion from physical 
media in space to matter, and back again to these media 
(in a circle), the collective sum total of energy in matter and 
in these media remaining at every instant constant, in ac- 
cordance with the principle of the conservation of energy. 
The cyclical processes thus taking place on a great scale in 
the Universe are imitated on a smaller scale in the ordinary 
interchanges of energy on the earth’s surface, or all the 
ordinary processes of “ work,” or the derivation of power, 
show themselves to be cyclical processes on the recognition 
of the stores of motion in space rendered necessary by the 
physical theory of gravitation. For suppose, for example, 
we derive power from the fall of water, and use it through 
machinery for lifting weights or elevating materials, — then 
the motion derived at the descent of the water comes from 
the store of motion in the gravific medium, and passes to 
