A metaphor we’re all familiar with is ‘The moon was a ghostly galleon tossed upon cloudy seas.’ What an image! Not that we think the moon is anything but a lump of rock but the comparison works on so many levels. Apart from the fact that you’d trash the precision of the poem’s rhythm, ‘The moon was like a ghostly galleon’ just doesn’t stir me up to the same extent.

David Niven’s autobiography (one of them) is called The Moon’s a Balloon. Again, it puts pictures directly into our minds.
The problem occurs when people don’t know that the word or phrase is a metaphor. One which I originally thought was brilliant was Juggernaut. I don’t mean the Marvel Comic Book creation but as it is currently used in British English meaning a huge lorry. Juggernaut is a statue, an idol, of a Hindu god and it was hauled through the streets on a massive cart under which devotees threw themselves in sacrifice to be crushed under the wheels. Someone – some unsung genius – coined the metaphor which compared this with the huge vehicles taking goods through tiny villages and the inadequate roads of small towns. How brilliant. We sacrifice our clean air, our buildings, our quality of life and the safety of our children, for the great god commerce. It’s a wonderful comparison and it works. The trouble is, many, possibly most, people now think that Juggernaut is simply a word which means lorry. Eventually, no doubt, that’s all it will be, and the wonderful imagery of the original metaphor will be lost.
I wish I knew who came up with that metaphor. I would like to shake that person’s hand. It’s wonderful, but because we don’t understand it, we’re losing it.
Thanks to Jonathan Hill for allowing me the use of his excellent 'balloon' photograph.