On Sky Hooks and Selfish Genes.
Metaphors and analogies are useful devices, great tools - if used correctly - to get the message across especially with regard to difficult or non intuitive concepts.
From Hoyle's Big Bang, to RD's selfish gene and Dennett's sky-hooks, scientists have managed to bring scientific concepts within the grasp of most non-scientists, helping us like a floater does an inexperienced swimmer hovering over the deep-end.
I particularly like the joke - I'm sure you all know it - about the two walkers in the woods who are about to be attacked by a bear and while one runs away the other stoops to put on his running spikes. You can't out-run the bear, scoffs the first runner. No, replies the spike-wearing runner, but I can out-run you. It really got the message across about evolution, for me.
What funologies and metaphors have you come across and what scientific concepts did they help you understand better?