1. This idea how got.
The mind being every day informed, by the senses, of the alteration of those simple ideas it
observes in things without; and taking notice how one comes to an end, and ceases to be, and another begins to
exist which was not before; reflecting also on what passes within itself, and observing a constant change of its
ideas, sometimes by the impression of outward objects on the senses, and sometimes by the determination of its
own choice; and concluding from what it has so constantly observed to have been, that the like changes will for
the future be made in the same things, by like agents, and by the like ways,--considers in one thing the possibility
of having any of its simple ideas changed, and in another the possibility of making that change; and so comes by
that idea which we call power. Thus we say, Fire has a power to melt gold, i.e., to destroy the consistency of its
insensible parts, and consequently its hardness, and make it fluid; and gold has a power to be melted; that the sun
has a power to blanch wax, and wax a power to be blanched by the sun, whereby the yellowness is destroyed, and
whiteness made to exist in its room. In which, and the like cases, the power we consider is in reference to the
change of perceivable ideas. For we cannot observe any alteration to be made in, or operation upon anything, but
by the observable change of its sensible ideas; nor conceive any alteration to be made, but by conceiving a change
of some of its ideas.
