I’m not saying it’s all metaphor, but it is, just about  – and vélophile though I am, if you were to press me on what our most important invention is, I would have to put metaphor first, even ahead of the bicycle.

It was something we were taught very badly at school: the focus was entirely on what distinguished metaphor from simile and how to tell them apart, as if the crucial thing was not what they did (which is essentially the same thing), but how they did it. To make matters worse, this approach presents metaphor as something distinctly suspect, not to say shady and dishonest: ‘You see, children, while a simile only says that something is like or as another thing, a metaphor says it actually is that thing’ (almost invariably followed up by the drear examples ‘he fought like a lion/the soldier was a lion in the fight.’) Regrettably, I find that Chambers – in all other respects the nonpareil of single-volume dictionaries – perpetuates this folly: ‘a figure of speech by which a thing is spoken of as being that which it only resembles, as when a ferocious person is called a tiger.’

This approach must have left many convinced, like Belloc’s schoolboy, that ‘metaphor’ is just a long Greek word for a lie, something no honest, plain-dealing person will have anything to do with.

Yet, as I say, metaphor is of central importance – not just as a ‘figure of speech’ (as they called it when I was young) but as a tool for thinking about the world, indeed for thinking about everything.

There are two definitions of metaphor that I have always kept by me since first I started to think seriously about the matter, which as accurately as I can reckon was about thirty-six years ago (on the upper floors of David Hume Tower, in a tutorial on Kant’s Critique of Aesthetic Judgement, a book I have still not succeeded in reading).

The first is from Aristotle, from the Poetics:

‘ but the greatest thing is to be a master of metaphor, for that shows the ability to see the similarity in dissimilar things.’

The second is from Vita Sackville-West, from a book she wrote on Marvell. I do not have it to hand, but the gist of it is this – speaking of the metaphysical poets, she says that they saw in metaphor the means to express ‘the unknown and dimly suspected Absolute in terms of the known concrete.’

I think these definitions make a good complementary pair – Aristotle is, as ever, ‘so very nice and dry’ – he gets right to the heart of the matter, ‘seeing the similarity in dissimilars.’

There is a paradox here, certainly – how can dissimilar things be similar? – but it is one that is easily explained in terms of another invention of Aristotle, his system of classification, where things are grouped according to general similarity but distinguished by specific difference: there is superficial difference – as between people, say, or mammals generally – but underlying similarity (in their skeletons, or the arrangement of their organs). To be a master of metaphor, by Aristotle’s definition, is to have a penetrating eye, one that sees through the beguiling surface appearance to the likeness that lies beneath.

But it is Sackville-West who brings out the real power of metaphor, which is creative, and renews the paradox in terms that are less easily resolved – this is not about seeing the similarity in dissimilar things, it is about expressing ‘the unknown… in terms of the known concrete.’ Here, a metaphor is like a bridge firmly rooted on one bank that half-way across vanishes into a mysterious fog. (The etymology of the word is from meta– beyond, after and pherein, to carry – hence something ‘carried beyond’ or ‘carried across’ – a metaphor is, literally, a ferry (a word that is surely from the same root, ultimately, via the German, fahren) – so perhaps my image should be Charon on the Styx)

It’s a fair assumption that Sackville-West’s definition owes something to Shakespeare:

here is the same paradox restated: for what else is ‘expressing the unknown in terms of the known concrete’ than ‘giving to airy nothing a local habitation and a name’?

If I am attempting to rescue metaphor from charges of dishonesty, then it seems I am not doing a very good job – and nowhere is the whiff of disrepute that hangs about poets and poetry because of metaphor better expressed (with unintentional hilarity) than in the ‘translation’ of the Shakespeare speech above into ‘modern text’ that is found in *Sparknotes ‘no fear Shakespeare’ :

‘Poets are always looking around like they’re having a fit, confusing the mundane with the otherworldly, and describing things in their writing that simply don’t exist.’

Surely not people that honest folk want anything to do with!

That seems like a good point to stop for coffee….