loose meanings annexed to them; and their ideas are very
uncertain and confused. No animal can put external bodies in
motion without the sentiment of a _nisus_ or endeavour; and
every animal has a sentiment or feeling from the stroke or blow
of an external object, that is in motion. These sensations,
which are merely animal, and from which we can _a priori_ draw
no inference, we are apt to transfer to inanimate objects, and
to suppose, that they have some such feelings, whenever they
transfer or receive motion. With regard to energies, which are
exerted, without our annexing to them any idea of communicated
motion, we consider only the constant experienced conjunction
of the events; and as we _feel_ a customary connexion between
the ideas, we transfer that feeling to the objects; as nothing
is more usual than to apply to external bodies every internal
sensation, which they occasion.

61. To recapitulate, therefore, the reasonings of this section: Every
idea is copied from some preceding impression or sentiment; and where we
cannot find any impression, we may be certain that there is no idea. In
all single instances of the operation of bodies or minds, there is
nothing that produces any impression, nor consequently can suggest any
idea of power or necessary connexion. But when many uniform instances
appear, and the same object is always followed by the same event; we
then begin to entertain the notion of cause and connexion. We then
_feel_ a new sentiment or impression, to wit, a customary connexion in
the thought or imagination between one object and its usual attendant;
and this sentiment is the original of that idea which we seek for. For
as this idea arises from a number of similar instances, and not from any
single instance, it must arise from that circumstance, in which the
number of instances differ from every individual instance. But this