Full Idea
Understanding a metaphor is as much a creative endeavour as making a metaphor, and as little guided by rules.
Gist of Idea
Understanding a metaphor is a creative act, with no rules
Source
Donald Davidson (What Metaphors Mean [1978], p.29)
Book Reference
'On Metaphor', ed/tr. Sacks,Sheldon [Chicago 1981], p.29
A Reaction
This is good news for literature studies courses. Davidson's point is that the metaphor itself only gives you a literal meaning, so it doesn't tell you how to interpret it. It seems an attractive proposal.