Metaphors are invaluable devices. They enable a writer to convey ideas briefly and vividly that might otherwise need pages of tedious exposition. What would become of us, in our present economic straits, without our targets, ceilings, blueprints, and bottlenecks? But metaphors are not without their dangers. Here are two.
One is that they are so attractive, especially when new. They sparkle like gems. They seem to say in a word just what we are trying laboriously to put across. It may be moreover that we are rather proud to have learned a new one, and want to show off. Thus new metaphors tend to be used indiscriminately and soon get stale, but not before they have elbowed out words perhaps more commonplace but with meanings more precise. Sometimes metaphors are so absurdly overtaxed that they become a laughing-stock and die of ridicule. That has been the fate of "exploring every avenue" and of "leaving no stone unturned". See Cliché.
Another danger in the use of metaphors is of falling into incongruity. So long at least as they are "live" metaphors, they must not be given a context that would be absurd if the words used metaphorically were being used literally. We must not refer to the biggest bottleneck when what we mean is the most troublesome one for that will obviously be the narrowest. We must not speak of "sterilising" land when what we mean is that it is to be left unbuilt on in order that it may continue to give us the fruits of the earth. We must not speak of "extending" a ceiling when what we mean is raising it. The statesman who said that sections of the population were being squeezed flat by inflation was not then in his happiest vein, nor was the writer who claimed for American sociology the distinction of having always immersed itself in concrete situations. We cannot but admit that there is no hope of checking the astonishing antics of target and of bringing that flighty word within reasonable bounds. But do not let its have any more metaphors getting out of hand like that.