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rational solution. No solution wliicli transcends these limits^ 
and resorts to the super-sensuous, is admissible. 
But, by the general consent of both the great divisions of 
modern philosophy, compliance with this demand is an impos- 
sibility. Those who are determined to ascend to the first 
cause of things may, if they please, call themselves Materialists, 
but must needs transcend the limits of sensuous experience. 
Nature presents our outward senses with nothing more than 
a succession of appearances, — phenomena. Suppose a line of 
billiard-balls, and let the outermost be struck by another ball 
impelled by some unseen hand : the motion will be transmitted 
from ball to ball in regular succession until the force is spent 
by friction. No one would think, in such a case, of attributing 
the motion of any one ball to its immediate predecessor in 
the line of movement. It is plain that the balls are mere 
vehicles of force, and not originant causes. They are, as 
regards their movement, but links in a chain of effects, where 
each indeed stands in the relation of a cause to those that 
follow, but is at the same time the mere effect of all that 
precede. Physical nature presents to our senses precisely such 
a chain of successive effects, the originant cause of which is 
hidden from us. To the philosophic eye the world does not 
seem to go of itself. True, the phenomena follow one another 
in an invariable order. But unless we go behind phenomena, 
unless we carry our thought back to the unseen power, — I 
myself should say to the unseen hand, — which first set the 
machine in motion, and still keeps it moving, we learn nothing 
more than the order of events. We only find, as Hume 
asserts, that the one does actually in fact follow the other. 
This is the whole that appears to the outward senses. The 
scenes of the universe are continually shifting, and one object 
follows another in uninterrupted succession ; but the power or 
force which actuates the whole machine is entirely concealed 
from us, and never discovers itself in any of the sensible 
qualities of body. In reality there is no part of nature that 
does ever by its sensible qualities discover any power or energy, 
or give us ground to imagine that it could produce anything, 
or be followed by any other object which we could denominate 
its effect.'’’* 
This is just one of the points on which the first impression 
of nearly every one wilt be against the doctrine of the philo- 
sophers j yet, if you will ponder the matter, remembering 
always that the question is as to what we know by means of 
the outward senses, you will, I think, be sure to agree in the 
* Hume, Essays, No, VII., “Of the Idea of Necessary Connexion.’’ 
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