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Chapter XXVI

Of Cause and Effect, and other Relations.
Whence their Ideas got.       §1. In the notice, that our Senses take of the constant Vicissitude
of Things, we cannot but observe, that several particular, both
Qualities, and Substances begin to exist; and that they receive this
their Existence, from the due Application and Operation of some
other Being. From this Observation, we get our Ideas of Cause and
Effect. That which produces any simple or complex Idea, we denote
by the general Name Cause; and that which is produced, Effect.
Thus finding, that in that Substance which we call Wax, Fluidity,
which is a simple Idea, that was not in it before, is constantly pro-
duced by the Application of a certain degree of Heat, we call the
simple Idea of Heat, in relation to Fluidity in Wax, the Cause of it,
and Fluidity the Effect. So also finding that the Substance, Wood,
which is a certain Collection of simple Ideas, so called, by the
Application of Fire, is turned into another Substance, called Ashes;
i.e. another complex Idea, consisting of a Collection of simple Ideas,
quite different from that complex Idea, which we call Wood; we
consider Fire, in relation to Ashes, as Cause, and the Ashes, as
Effect. So that whatever is considered by us, to conduce or operate,
to the producing any particular simple Idea, or Collection of simple
Ideas, whether Substance, or Mode, which did not before exist, hath
thereby in our Minds the relation of a Cause, and so is denominated
by us.
Locke Hum II, 26, §1, p. 324