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eud that Hume is in the right. When^ indeed^ experience 
has taught us that any natural occurrence has been invariably 
followed by some other^ then^ assuming as we all do in 
modern times the perfect uniformity of nature, we confidently 
expect that the appearance of the former event, whenever it 
occurs, will be infallibly followed by its regular consequence ; 
and in common speech we couple the two together as cause 
and effect ; though, if we reflect upon the matter, we easily 
perceive that the so-called cause is itself a mere effect of some- 
thing antecedent. We must not delude ourselves with the 
metaphor of a self-acting machine, for, in truth, there is no 
such thing. No machine goes of itself, or is more than an 
arrangement for transmitting force, — like the intermediate 
billiard-balls. We may, then, take it as established, that the 
notion of producing cause or force is not given us by the 
senses, nor to be found in external nature, for this is the con- 
current verdict of all the schools of modern philosophy. On 
this account, Hume and his followers, including Mill aud 
Herbert Spencer, consistently maintain that the knowledge of 
a producing cause is beyond the scope of science. Knowledge 
of the order of phenomena is all that, in their opinion, is 
possible to the human intellect. 
But, despite the caveats of these philosophers, the dynamic 
idea, the notion of a force in nature, maintains its hold upon 
the human mind. We are impelled by an irresistible 
necessity to demand a cause of every occurrence. May I 
quote Martineau as saying, By an irresistible law of 
thought all phenomena present themselves to us as the ex- 
pression of power, and refer us to a causal ground whence 
they issue. This dynamic source [this origin of power] we 
neither see, nor hear, nor feel j it is given in thought , — 
supplied by the spontaneous activity of the mind itself as the 
correlative prefix to [i.e., inseparably coupled in the mind 
with] the phenomenon observed. By the general acknow- 
ledgment of philosophers this idea is so strictly a necessary 
idea as to be entirely irremovable from the conception of any 
change : to cut the tie between them, and think of phenomena 
as not effects, is impossible, in fact, even to the very writers 
who propose it in theory A productive power, though un- 
revealed to sense, must, then, be sought for behind the things 
produced. To revert to our well-worn illustration,' — the move- 
ment of the first billiard-ball must be accounted for, or 
nothing is finally explained. 
In one respect the backward search for the primal cause of 
all things has, of late, been made easier for the Materialist, 
and a guess of ancient science has been confirmed. Modern 
