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The clearest Idea of active Power had from Spirit.       §4. We are abundantly furnished with the Idea of passive Power,
by almost all sorts of sensible things. In most of them we cannot
— 235 —
avoid observing their sensible Qualities, nay their very Substances
to be in a continual flux: And therefore with reason we look on them
as liable still to the same Change. Nor have we of active Power
(which is the more proper signification of the word Power) fewer
instances. Since whatever Change is observed, the Mind must
collect a Power somewhere, able to make that Change, as well as a
possibility in the thing it self to receive it. But yet, if we will con-
sider it attentively, Bodies, by our Senses, do not afford us so clear
and distinct an Idea of active Power, as we have from reflection on the
Operations of our Minds. For all Power relating to Action, and there
being but two sorts of Action, whereof we have any Idea, viz.
Thinking and Motion, let us consider whence we have the clearest
Ideas of the Powers, which produce these Actions. 1. Of Thinking,
Body affords us no Idea at all, it is only from Reflection that we have
that: 2. Neither have we from Body any Idea of the beginning of
Motion. A Body at rest affords us no Idea of any active Power to move;
and when it is set in motion it self, that Motion is rather a Passion,
than an Action in it. For when the Ball obeys the stroke of a Billiard-
stick, it is not any action of the Ball, but bare passion: Also when by
impulse it sets another Ball in motion, that lay in its way, it only
communicates the motion it had received from another, and loses
in it self so much, as the other received; which gives us but a very
obscure Idea of an active Power of moving in Body, whilst we observe
it only to transfer, but not produce any motion. For it is but a very
obscure Idea of Power, which reaches not the Production of the
Action, but the Continuation of the Passion. For so is motion in a
Body impelled by another: The continuation of the Alteration made
in it from rest to motion being little more an Action, than the con-
tinuation of the Alteration of its Figure by the same blow is an
Action. The Idea of the beginning of motion, we have only from re-
flection on what passes in our selves, where we find by Experience,
that barely by willing it, barely by a thought of the Mind, we can
move the parts of our Bodies, which were before at rest. So that it
seems to me, we have from the observation of the operation of
Bodies by our Senses, but a very imperfect obscure Idea of active
Power, since they afford us not any Idea in themselves of the Power
to begin any Action, either motion or thought. But if, from the
Impulse Bodies are observed to make one upon another, any one
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thinks he has a clear Idea of Power, it serves as well to my purpose,
Sensation being one of those ways, whereby the mind comes by its
Ideas: Only I thought it worth while to consider here by the way,
whether the mind doth not receive its Idea of active Power clearer
from reflection on its own Operations, than it doth from any ex-
ternal Sensation.
Locke Hum II, 21, §4, pp. 234-235-236