ve the idea of causes and necessity, though
perhaps we may avoid those expressions. Motion in one body in all past
instances, that have fallen under our observation, is followed upon
impulse by motion in another. It is impossible for the mind to penetrate
farther. From this constant union it forms the idea of cause and
effect, and by its influence feels the necessity. As there is the same
constancy, and the same influence in what we call moral evidence, I ask
no more. What remains can only be a dispute of words.

And indeed, when we consider how aptly natural and moral evidence cement
together, and form only one chain of argument betwixt them, 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 from the
obstinacy of the goaler, as from the walls and bars with which he is
surrounded; and in all attempts for his freedom chuses 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 ax 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
betwixt them in passing from one link to another; nor is less certain of
the future event than if it were connected with the present impressions
of the memory and 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,
volitions and actions; or figure and motion. We may change the names of
things; but their nature and their operation on the understanding never
change.

I dare be positive no one will ever endeavour to refute these reasonings
otherwise than by altering my definitions, and assigning a different
meaning to the terms of cause, and effect, and necessity, and liberty,
and chance. According to my definitions, necessity makes an essential
part of causation; and consequently liberty, by removing necessity,
removes also causes, and is t