Full Idea
What is the difference between fiction and belief? It can't be a peculiar idea annexed to a conception which commands our assent, and is wanting to fiction, for then the mind could voluntarily annex this idea to any fiction, and believe what it pleases.
Gist of Idea
Belief can't be a concept plus an idea, or we could add the idea to fictions
Source
David Hume (Enquiry Conc Human Understanding [1748], V.II.39)
Book Reference
Hume,David: 'Enquiries Conc. Human Understanding, Morals', ed/tr. Selby-Bigge/Nidditch [OUP 1975], p.48