Full Idea
I never can catch myself at any time without a perception, and never can observe any thing but the perception.
Gist of Idea
Introspection always discovers perceptions, and never a Self without perceptions
Source
David Hume (Treatise of Human Nature [1739], I.IV.6)
Book Reference
'Personal Identity', ed/tr. Perry,John [University of California 1975], p.162
A Reaction
The first half can hardly be denied, but I think the second half is just false. What you observe is not just a raw neutral sense-datum, floating in nothing, but a sense-datum that is deeply coloured by MY interests, interpretations and values.
Related Idea
Idea 18463 Successful introspection reveals the substrate along with the object of thought [Porphyry]