Leading Article: Rhyme and reason

Quod spiro et placeo tuum est, said Horace - "it is because of you I make poetry". For poets down the ages "you" more often than not was she: Catullus's Lesbia, Burns's bonnie Lesley, Goethe's Lottie, Betjeman's Joan Hunter Dunn. Traditionally, poets have sought inspiration outside themselves. They bend a figure from nature, from a brook, from a face. They hear a rhyme in a clock (Pope) or a step (Baudelaire).

According to Dr Felix Post, writing in the British Journal of Psychiatry, this is how poets work. They are, it appears, more sociable and less self- preoccupied than other artists. According to his (not entirely rigorous and scientific) study of poets' characters, they are much less "antisocial, histrionic and narcissistic" not just than writers of prose and plays but even than the population at large. So perhaps they do, like Donne contemplating heaven - or his mistress's bum - get their inspiration from without.

Yet that is not the end of the story. Poets, Dr Post opines, exhibit much higher levels of severe manic depression than other kinds of writer. But they show lower levels of mild depression, alcoholism, sexual dysfunction and what the psychiatrists charmingly call personality deviations. Dr Post's consulting couch throws up the following explanation. Writers of novels or plays - Dr Post's study, it should be said, is of the greats rather than authors from the Jilly Cooper and Jeffrey Archer school - enter into the heads of their characters and this leads to greater "inner turmoil". Poets, by contrast, are connoisseurs of language rather than character. It seems the pursuit of a metaphor is less stressful than working out a plot.

But this is all counter-intuitive. Don't poets inhabit garrets along with the cast of Bohemian life, or live the romantic life a l'outrance with Cavafy or Rilke? The fact is generalisation across the writing disciplines is fraught with difficulty. As for Dr Post's suggestion that poets don't drink or screw around: didn't Dylan Thomas write that book aided and abetted by Dryden and Jonson? For every Sylvia Plath the world of verse can offer upstanding characters like Tennyson; for every drug-abusing Coleridge a clean-living fellow such as Walt Whitman; for every brash young Shelley a wise old Homer.

Dr Post speculates that creative work of the imagination is associated with "excessively" high activity in the neural networks but is not entirely sure which way the causation runs. That sounds suspiciously like a very old observation about artists of all kinds. They are all slightly unhinged, slightly manic. That is what makes them strive to see themselves, us and the world more clearly than we do.