continuance of one object? In this particular, then, the
memory not only discovers the identity, but also contributes to
its production, by producing the relation of resemblance among the
perceptions. The case is the same whether we consider ourselves or
others.

As to causation; we may observe, that the true idea of the human mind,
is to consider it as a system of different perceptions or different
existences, which are linked together by the relation of cause and
effect, and mutually produce, destroy, influence, and modify each other.
Our impressions give rise to their correspondent ideas; said these ideas
in their turn produce other impressions. One thought chaces another,
and draws after it a third, by which it is expelled in its turn. In this
respect, I cannot compare the soul more properly to any thing than to a
republic or commonwealth, in which the several members are united by the
reciprocal ties of government and subordination, and give rise to other
persons, who propagate the same republic in the incessant changes of
its parts. And as the same individual republic may not only change its
members, but also its laws and constitutions; in like manner the
same person may vary his character and disposition, as well as his
impressions and ideas, without losing his identity. Whatever changes
he endures, his several parts are still connected by the relation of
causation. And in this view our identity with regard to the passions
serves to corroborate that with regard to the imagination, by the making
our distant perceptions influence each other, and by giving us a present
concern for our past or future pains or pleasures.

As a memory alone acquaints us with the continuance and extent of this
succession of perceptions, it is to be considered, upon that account
chiefly, as the source of personal identity. Had we no memory, we never
should have any notion of causation, nor consequently of that chain of
causes and effects, which constitute our self or person. But having once
acquired this notion of causation from the memory, we can extend the
same chain of causes, and consequently the identity of car persons
beyond our memory, and can comprehend times, and circumstances, and
actions, which we have entirely forgot, but suppose in general to have
existed. For how few of our past actions are there, of which we have
any memory? Who can tell me, for instance, what were his thoughts and
actions on the 1st of January 1715, the