BOOK II PART III
gle instance the ultimate connexion of any ob-
jects is discoverable, either by our senses or rea-
son, and that we can never penetrate so far into
the essence and construction of bodies, as to
perceive the principle, on which their mutual
influence depends. It is their constant union
alone, with which we are acquainted; and it
is from the constant union the necessity arises.
If objects had nor an uniform and regular con-
junction with each other, we should never ar-
rive at any idea of cause and effect; and even af-
ter all, the necessity, which enters into that idea,
is nothing but a determination of the mind to
pass from one object to its usual attendant, and
infer the existence of one from that of the other.
Here then are two particulars, which we are to
consider as essential to necessity, viz, the con-
stant union and the inference of the mind; and
wherever we discover these we must acknowl-