Full Idea
The entire property of a concept consists in nothing more than what has been begged and borrowed from perceptual knowledge, which is the true and inexhaustible source of all insight.
Gist of Idea
All of our concepts are borrowed from perceptual knowledge
Source
Arthur Schopenhauer (Parerga and Paralipomena [1851], I:9)
Book Reference
Schopenhauer,Arthur: 'Essays and Aphorisms [from Pand P]', ed/tr. Hollingdale,R.J. [Penguin 1970], p.118
A Reaction
Schopenhauer is usually seen as a sort of idealist, but this is a full endorsement of the empirical view of concepts, to which I largely subscribe. Note that he talks of 'knowledge', rather than of 'experience'.