Full Idea
When I enter most intimately into myself I always stumble on some particular perception or other, of heat or cold, love or hatred, pain or pleasure. I never can catch myself at any time without a perception, and never observe any thing but the perception.
Gist of Idea
When I introspect I can only observe my perceptions, and never a self which has them
Source
David Hume (Treatise of Human Nature [1739], I.IV.6)
Book Reference
Hume,David: 'A Treatise of Human Nature', ed/tr. Selby-Bigge/Nidditch [OUP 1978], p.252
A Reaction
It isn't like looking for your car in the car park. The prior question should be: assuming you do have a persisting self, what would you expect introspection to reveal about it?