to produce particular sentiments, and if these sentiments had no
constant operation on actions? And with what pretence could we employ
our _criticism_ upon any poet or polite author, if we could not
pronounce the conduct and sentiments of his actors either natural or
unnatural to such characters, and in such circumstances? It seems almost
impossible, therefore, to engage either in science or action of any kind
without acknowledging the doctrine of necessity, and this _inference_
from motive to voluntary actions, from characters to conduct.

And indeed, when we consider how aptly _natural_ and _moral_ evidence
link together, and form only one chain of argument, we shall make no
scruple to allow that they are of the same nature, and derived from the
same principles. A prisoner who has neither money nor interest,
discovers the impossibility of his escape, as well when he considers the
obstinacy of the gaoler, as the walls and bars with which he is
surrounded; and, in all attempts for his freedom, chooses rather to work
upon the stone and iron of the one, than upon the inflexible nature of
the other. The same prisoner, when conducted to the scaffold, foresees
his death as certainly from the constancy and fidelity of his guards, as
from the operation of the axe or wheel. His mind runs along a certain
train of ideas: The refusal of the soldiers to consent to his escape;
the action of the executioner; the separation of the head and body;
bleeding, convulsive motions, and death. Here is a connected chain of
natural causes and voluntary actions; but the mind feels no difference
between them in passing from one link to another: Nor is less certain of
the future event than if it were connected with the objects present to
the memory or senses, by a train of causes, cemented together by what we
are pleased to call a _physical_ necessity. The same experienced union
has the same effect on the mind, whether the united objects be motives,
volition, and actions; or figure and motion. We may change the name of