Full Idea
A metaphor works when it satisfies a purpose, namely, understanding an aspect of the concept.
Gist of Idea
Metaphors help us to understand aspects of concepts
Source
G Lakoff / M Johnson (Metaphors We Live By [1980], 17)
A Reaction
There is a tension in their account between metaphors as the creators of concepts, and as means for understanding concepts. I'm trying to fit together their nice account of metaphor with the idea of concepts as mental files (qv).
Book Reference
Lakoff,G/Johnson,M: 'Metaphors We Live By' [Chicago 2003], p.97