Full Idea
Upon the appearance of the picture of an absent friend, our idea of him is evidently enlivened by the resemblance.
Gist of Idea
A picture of a friend strengthens our idea of him, by resemblance
Source
David Hume (Enquiry Conc Human Understanding [1748], V.II.41)
Book Reference
Hume,David: 'Enquiries Conc. Human Understanding, Morals', ed/tr. Selby-Bigge/Nidditch [OUP 1975], p.51