hought, or
a different position of parts give rise to a different passion or
reflection. Nay it is not only possible we may have such an experience,
but it is certain we have it; since every one may perceive, that the
different dispositions of his body change his thoughts and sentiments.
And should it be said, that this depends on the union of soul and
body; I would answer, that we must separate the question concerning the
substance of the mind from that concerning the cause of its thought; and
that confining ourselves to the latter question we find by the comparing
their ideas, that thought and motion are different from each other,
and by experience, that they are constantly united; which being all
the circumstances, that enter into the idea of cause and effect, when
applied to the operations of matter, we may certainly conclude, that
motion may be, and actually is, the cause of thought and perception.

There seems only this dilemma left us in the present case; either to
assert, that nothing can be the cause of another, but where the mind can
perceive the connexion in its idea of the objects: Or to maintain, that
all objects, which we find constantly conjoined, are upon that account
to be regarded as causes and effects. If we choose the first part of the
dilemma, these are the consequences. First, We in reality affirm,
that there is no such thing in the universe as a cause or productive
principle, not even the deity himself; since our idea of that supreme
Being is derived from particular impressions, none of which contain any
efficacy, nor seem to have any connexion with any other existence. As to
what may be said, that the connexion betwixt the idea of an infinitely
powerful being, and that of any effect, which he wills, is necessary and
unavoidable; I answer, that we have no idea of a being endowed with
any power, much less of one endowed with infinite power. But if we will
change expressions, we can only define power by connexion; and then in
saying, that the idea, of an infinitely powerful being is connected with
that of every effect, which he wills, we really do no more than
assert, that a being, whose volition is connected with every effect,
is connected with every effect: which is an identical proposition, and
gives us no insight into the nature of this power or connexion. But,
secondly, supposing, that the deity were the great and efficacious
principle, which supplies the deficiency of all causes, this leads us