Literary devices and figures of speech are not prominent in routine research papers, but are more likely in editorials and opinion pieces. Used properly, they enliven writing, which is why columnists – both in newspapers and magazines and in their medical equivalents – use them.

Metaphor is the most important and widespread figure of speech, and is (COD) the application of name or descriptive term to an object or action to which it is imaginatively but not literally applicable. It suggests a shared property. It is metaphorical when we write that a drug ‘locks onto’ a receptor, suggesting that drugs and receptors are like keys and locks. In previous chapters we have mentioned drawback (its original meaning now less well-known than its metaphorical one), elevated from bishop to archbishop, falling into groups, hormones having a role, a graveyard full of failed treatments, focusing a service, examining cars in depth, and a cocktail of drugs.

There are two reasons to be wary of metaphors: first, readers may misinterpret them, especially EAL readers, who may not understand them at all; and second, metaphors have a tendency to descend pretty quickly to cliché. Metaphors are intended to enliven writing; clichés, because they are overused, deaden it. There is no strict definition of cliché; nor is there a list in which to check whether a chosen metaphor has degenerated to cliché. As The Economist’s guide (see reference books) points out, ‘clichés weren’t always clichéd. The first person to use window of opportunity . . . was justly pleased with himself. [It] is a strong, vivid expression – or was. The trouble is that such expressions have been copied so often that they have lost their vividness.