It is therefore by EXPERIENCE only, that we can infer the existence of one
object from that of another. The nature of experience is this. We
remember to have had frequent instances of the existence of one species
of objects; and also remember, that the individuals of another species of
objects have always attended them, and have existed in a regular order of
contiguity and succession with regard to them. Thus we remember, to have
seen that species of object we call flame, and to have felt that species
of sensation we call heat. We likewise call to mind their constant
conjunction in all past instances. Without any farther ceremony, we call
the one cause and the other effect, and infer the existence of the one
from that of the other. In all those instances, from which we learn the
conjunction of particular causes and effects, both the causes and effects
have been perceived by the senses, and are remembered But in all cases,
wherein we reason concerning them, there is only one perceived or
remembered, and the other is supplyed in conformity to our past
experience.

Thus in advancing we have insensibly discovered a new relation betwixt
cause and effect, when we least expected it, and were entirely employed
upon another subject. This relation is their CONSTANT CONJUNCTION.
Contiguity and succession are not sufficient to make us pronounce any two
objects to be cause and effect, unless we perceive, that these two
relations are preserved in several instances. We may now see the
advantage of quitting the direct survey of this relation, in order to
discover the nature of that necessary connexion, which makes so essential
a part of it. There are hopes, that by this means we may at last arrive
at our proposed end; though to tell the truth, this new-discovered
relation of a constant conjunction seems to advance us but very little in
our way. For it implies no more than this, that like objects have always
been placed in like relations of contiguity and succession; and it seems