I confess power includes in it some kind of relation (a relation to action or change,) as indeed which of our ideas of what kind soever, when attentively considered, does not.  For, our ideas of extension, duration, and number, do they not all contain in them a secret relation of the parts?  Figure and motion have something relative in them much more visibly.  And sensible qualities, as colours and smells, &c. what are they but the powers of different bodies, in relation to our perception, &c.?  And, if considered in the things themselves, do they not depend on the bulk, figure, texture, and motion of the parts?  All which include some kind of relation in them.  Our idea therefore of power, I think, may well have a place amongst other simple ideas, and be considered as one of them; being one of those that make a principal ingredient in our complex ideas of substances, as we shall hereafter have occasion to observe.

4.  The clearest Idea of active Power had from Spirit.

Of passive power all sensible things abundantly furnish us with sensible ideas, whose sensible qualities and beings we find to be in 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 itself to receive it.  But yet, if we will consider 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 an 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 itself, that motion is rather a passion than an action in it.  For, when the ball obeys the motion 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 itself 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 continuation