which it has arisen
is our inner perception that our thought remains constant in the repeated
experience of the same group of qualities (whenever I see sugar, _I do the
same thing_, that is, I combine the qualities white color, sweet taste,
hardness, etc., with one another), or the impression of a uniform
combination of ideas. The idea of substance becomes erroneous through the
fact that we refer it not to the inner activity of representation, to which
it rightly belongs, but to the external group of qualities, and make it
a real, permanent substratum for the latter. Mental substances disappear
along with material substances. The soul or mind is, in reality, nothing
more than the sum of our inner states, a collection of ideas which flow
on in a continuous and regular stream; it is like a stage, across which
feelings, perceptions, thoughts, and volitions are passing while it does
not itself come into sight. A permanent self or ego, as a substratum of
ideas, is not perceived; there is no invariable, permanent impression. That
which leads to the assumption of personal identity is only the frequent
repetition of similar trains of ideas, and the gradual succession of
our ideas, which is easily confused with constancy. Thus robbed of its
substantiality, the soul has no further claims to immateriality and
immortality, and suicide ceases to be a crime.[1]

[Footnote 1: Cf. the essays on _Suicide_ and the _Immortality of the Soul_,
1783, whose authorship by Hume, however, is not absolutely established [of.
Green and Grose, as above, p. 221, note first.--TR.]]

Is Hume roundly to be called a skeptic? [1] He never impugned the validity
of mathematical reasonings, nor experimental truths concerning matters of
fact; in regard to the former his thought is rationalistic, in regard to
the latter it is empirical or, more accurately, sensationalistic. His
attitude toward the empirical sciences of nature and of mind is that of a
semi-skeptic or probabilist, in so far as they go beyond the establishment
of facts to the proof of connections under law and to inferences concerning
the future. Habit is for him a safe guide for life, although it does not go
beyond probabilities; absolute knowledge is unattainable for us, but
not indispensable. Toward metaphysics, as an alleged science of the
suprasensible, he takes up an entirely negative attitude. If an argument
from experience is to be assured of merely that degree of probability which
is su