Useful metaphors for tackling problems in teaching and learning. (gse.harvard.edu)
The chief instrument for cultural change is «a talent for speaking differently, rather than for arguing well» and intellectual and moral progress can be charted as «a history of increasingly useful metaphors rather than of increasing understanding of how things really are» (CIS 9). (religion-online.org)
This is really in a different context («buy and hold», which I've decidedly mixed feelings about), but it's a v useful metaphor to remember. (wexboy.wordpress.com)