If this definition be esteemed
defective, because drawn from objects foreign to the cause, we may
substitute this other definition in its place, viz. A CAUSE is an object
precedent and contiguous to another, and so united with it, that the
idea, of the one determines the mind to form the idea of the other, and
the impression of the one to form a more lively idea of the other. 2
should this definition also be rejected for the same reason, I know no
other remedy, than that the persons, who express this delicacy, should
substitute a juster definition in its place. But for my part I must own
my incapacity for such an undertaking. When I examine with the utmost
accuracy those objects, which are commonly denominated causes and
effects, I find, in considering a single instance, that the one object
is precedent and contiguous to the other; and in inlarging my view
to consider several instances, I find only, that like objects are
constantly placed in like relations of succession and contiguity. Again,
when I consider the influence of this constant conjunction, I perceive,
that such a relation can never be an object of reasoning, and can never
operate upon the mind, but by means of custom, which determines the
imagination to make a transition from the idea of one object to that
of its usual attendant, and from the impression of one to a more lively
idea of the other. However extraordinary these sentiments may appear,
I think it fruitless to trouble myself with any farther enquiry or
reasoning upon the subject, but shall repose myself on them as on
established maxims.

It will only be proper, before we leave this subject, to draw some
corrollaries from it, by which we may remove several prejudices and
popular errors, that have very much prevailed in philosophy. First, We
may learn from the foregoing, doctrine, that all causes are of the
same kind, and that in particular there is no foundation for that
distinction, which we sometimes make betwixt efficient causes and causes
sine qua non; or betwixt efficient causes, and formal, and material, and
exemplary, and final causes. For as our idea of efficiency is derived
from the constant conjunction of two objects, wherever this is observed,
the cause is efficient; and where it is not, there can never be a cause
of any kind. For the same reason we must reject the distinction betwixt
cause and occasion, when supposed to signify any thing essentially
different from each other. If constant