________________
The relation
of concomi
tant varia
tion: its diffi
culties.
comitant variation, for the change in one manifests itself in a corresponding change in the other. But this relation is not possible and cannot be satisfactorily explained, if they be not ultimately the same, or to put it in other words, if a common blood does not run through their veins. But this is nega
tived by the hypothesis, for by ex-hypothese they have been assumed to be two distinct worlds having nothing in common.
Others, in order to escape from these difficulties, may suppose that some influence in some form or other, passes into the thing called effect and produces changes in the The interaction is not apparent here as in the former case, but real. The cause exerts some influence upon something else and thereby produces changes in the same which we call effect.
same.
This at first sight seems to possess much of plausibility, though it cannot stand to a careful scrutiny of reason. The difficulty here is this: where does the influence rest before its being received by the thing for which it is meant? We cannot conceive of any influence passing out of a thing and
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