Full Idea
Necessity …is nothing but an internal impression of the mind, or a determination to carry our thoughts from one object to another.
Gist of Idea
Necessity only exists in the mind, and not in objects
Source
David Hume (Treatise of Human Nature [1739], I.III.16)
Book Reference
Hume,David: 'A Treatise of Human Nature', ed/tr. Selby-Bigge/Nidditch [OUP 1978], p.165
A Reaction
The classic statement of the empiricist position. Personally I don't believe it. Non-mental necessities are likely to be natural, or to be features of 'Platonic' objects. A big issue…