Full Idea
When we look towards external objects, and consider the operation of causes, we are never able to discover any power or necessary connexion, any quality which binds the effect to the cause.
Gist of Idea
In observing causes we can never observe any necessary connections or binding qualities
Source
David Hume (Enquiry Conc Human Understanding [1748], VII.I.50)
Book Reference
Hume,David: 'Enquiries Conc. Human Understanding, Morals', ed/tr. Selby-Bigge/Nidditch [OUP 1975], p.63