Full Idea
The difference between real things, and chimeras formed by the imagination, or the visions of a dream, is that the latter are faint and indistinct.
Clarification
A 'chimera' is a mythical beast
Gist of Idea
Real things and imaginary or dreamed things differ because the latter are much fainter
Source
George Berkeley (Three Dialogues of Hylas and Philonous [1713], III p.225)
Book Reference
Berkeley,George: 'The Principles of Human Knowledge etc.', ed/tr. Warnock,G.J. [Fontana 1962], p.225
A Reaction
In Hume this becomes 'impressions' and 'ideas'. It does raise the question of WHY some ideas are not as faint as others.