m one object to another.
Without considering it in this view, we can never arrive at the most
distant notion of it, or be able to attribute it either to external or
internal objects, to spirit or body, to causes or effects.

The necessary connexion betwixt causes and effects is the foundation of
our inference from one to the other. The foundation of our inference is
the transition arising from the accustomed union. These are, therefore,
the same.

The idea of necessity arises from some impression. There is no
impression conveyed by our senses, which can give rise to that idea. It
must, therefore, be derived from some internal impression, or impression
of reflection. There is no internal impression, which has any relation
to the present business, but that propensity, which custom produces, to
pass from an object to the idea of its usual attendant. This therefore
is the essence of necessity. Upon the whole, necessity is something,
that exists in the mind, not in objects; nor is it possible for us ever
to form the most distant idea of it, considered as a quality in bodies.
Either we have no idea of necessity, or necessity is nothing but that
determination of the thought to pass from causes to effects, and from
effects to causes, according to their experienced union.

Thus as the necessity, which makes two times two equal to four, or three
angles of a triangle equal to two right ones, lies only in the act of
the understanding, by which we consider and compare these ideas; in like
manner the necessity or power, which unites causes and effects, lies
in the determination of the mind to pass from the one to the other. The
efficacy or energy of causes is neither placed in the causes themselves,
nor in the deity, nor in the concurrence of these two principles; but
belongs entirely to the soul, which considers the union of two or more
objects in all past instances. It is here that the real power of causes
is placed along with their connexion and necessity.

I am sensible, that of all the paradoxes, which I, have had, or shall
hereafter have occasion to advance in the course of this treatise, the
present one is the most violent, and that it is merely by dint of solid
proof and reasoning I can ever hope it will have admission, and overcome
the inveterate prejudices of mankind. Before we are reconciled to this
doctrine, how often must we repeat to ourselves, that the simple view of
any two objects or actions, however related, can