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with planet,, man with man. Without ether there could be no 
communication in the universe : no light, no heat, no pheno- 
menon of motion. 
These inferences, I repeat, we may accept whatever be our 
theory as to the influence of ether on ponderable matter, or of 
such matter upon ether. We may admit, if we like, two forces, 
earth force and sun force ; we may believe in the inherent at- 
traction of the particles of ponderable matter for each other, 
and follow out motion as mere vibration or disturbance of the 
ethereal fluid amongst those particles; or we may look 
with Metcalfe on the ether itself as a self-acting principle or 
agency, combining with the particles of ponderable matter and 
repelling its own particles. We may say that light is actual 
matter radiating from the sun, or we may say it is a roll of 
ether- wave set in motion by the sun ! We may urge that 
caloric light and electricity are all forms of motion, and that 
the equivalent value of each is determinable ; or we may insist 
that caloric light and electricity are one subtle form of matter 
exerting differing influences on ponderable substance, and 
that motion is but the effect of the active principle upon pon- 
derable matter. 
We may, I repeat, accept these various readings, and if we 
think over them calmly, may claim for them almost an equal 
share of probability and value. By either we are driven back 
to a primary question, which is final. Suppose the particles 
of ponderable matter possess the force of cohesion, i. e ., attrac- 
tion the one for the other, what is that attraction? Or, 
suppose an active ether possessing attraction for ponderable 
matter and repelling its own particles ; what is this power of 
attraction and repulsion in the ether ? Suppose the sun has 
force — and who shall say it has not — whence the force ? 
Suppose we know — and we do know — that there are burning 
in the sun certain metals, which must, by their combustion, 
liberate force, whence comes the force that is being liberated 
by the burning metals ? Whence the sun itself, were a question 
as difficult to interpret. 
And there is one other subject, respecting which, on the ac- 
ceptance of either of the two theories, we have no clear explana- 
tion afforded. I refer to the construction of ponderable matter 
on given types or forms. There cannot be a doubt that form 
results out of motion of ponderable matter, and there can scarcely 
less be a doubt that it is the tendency of matter to be thrown 
by motion into the form of a sphere : the planets have clearly 
resulted from motion; the blood-cell clearly results from motion ; 
and all forms, atween these in magnitude, or greater or lesser, 
result equally from motion and possess the same characteristics. 
Whenever there is departure from the sphere, there has been 
