Poetry: Rhyme and reason

Even after 400 years, Shakespeare's Sonnet 130 is a funny, unconventional take on love poetry. Writers commonly use the sonnet to praise a lover's beauty by using flowery language and extended similes to describe their inamorata's beauties. Because of Shakespeare's ironic, unromantic stance the sonnet smuggles in something very close to sentimentality: a sincere love poem about a real, rather than idealised, woman.

This is a classic example of the "English" sonnet - fourteen lines, divided into three sets of four. Almost every line is what is technically called an iambic pentameter - meaning it has five beats. The iambic pentameter is the commonest form of English metre, and some critics have thought its popularity derives from its similarity to a heart-beat.

The first line is mildly mucky. "Nothing" is a euphemism for female genitals.

The second line changes the rhythm subtly, with a tripping beginning that establishes a certain light, wry tone. The long vowels in "far" and "more" are almost sarcastic.

The next two lines have prompted more speculation than any others in Shakespeare's sonnets, as they give us a physical description of the so-called Dark Lady, who was the object of his desire. "Dun" means grey or brown. The combination of "wiry black" hair and non-white skin has led to a great deal of speculation about Shakespeare's African mistress.

"Dun" and "head" that end the lines are dull, thudding monosyllables. You couldn't get further from the ornate and aureate language of Shakespeare's predecessors, with their panegyrics on crystal eyes and alabaster skin. The interjection "why then" seems almost throwaway, but in fact carefully creates the tone of informal mocking badinage. The easy style displays Shakespeare's dexterous use of language. There's a careful assonance between "hair" and "wire", which reinforces the idea that superficially similar things can be very different. In this next section each physical feature is given two lines rather than one, each feature gets an unrhymed couplet, making the poem feel more relaxed as Shakespeare warms to his theme.

Lines 7 and 8 are perhaps the most shocking in the poem, as Shakespeare moves from lack of beauty to positive ugliness. There's a taunting feel to line 8, reinforced by the hissing "s" and the rolling "r" and the switch from clipped vowels to the elongated and provocative "reeks".

Before the conclusion, we get only one word of praise to the mistress - "I love to hear her speak". A feminist reading of the poem might observe that rather than physical beauty, what Shakespeare praises is her mind shown forth in language, even if he undercuts the compliment by claiming music is a more beautiful sound. In the final comparison between the mistress and the goddess there is a superb example of how Shakespeare imbues the very sound of the words with meaning. The alliteration on "g" (grant, goddess, go, ground) mimics the mistress's ungainly walk. Line 12 is particularly self-conscious: when Shakespeare tells us his mistress "treads on the ground" he is literally bringing her down to earth, just as the poem has been doing throughout.

The final lines of the sonnet are both a conclusion and a sting in the tail. They are "despite" writ large. It is the first time we get a mention of "love" in the entire poem; and the invocation to "heaven" is starkly at odds with the more traditional and pompous use of Cupid, Aphrodite, Venus and Eros. The poem is as unembellished as he claims his mistress is. Indeed, the most "poetic" line is the line disavowing poetry. His lover is fine as any woman "belied with false compare" - any woman flattered and misrepresented by fancy poetry.

Peggy Hughes of the Scottish Poetry Library examines what gives a poem its extraordinary power

I like seafood, but I can't abide oysters. I'd consider myself a vegetable fan, but I wouldn't thank you for an aubergine. Such rich pickings from all over the world, so many ways of skinning a chicken: the options are wonderfully endless.

Poetry is not unlike food. There's a poem for every appetite and palate, and one poem, and let's call that poem "Rice Pudding" or "Haggis", may never be for you, no matter how it's served, or how many other people might disagree.

Poetry is open to interpretation and opinion, even if a teacher in a room aromatic with eau d'adolesent oxters made you believe otherwise. A poem can satisfy all manner of cravings. Scottish poet W S Graham wrote:

The spaces in the poem are yours.

They are the place where you

Can enter as yourself alone

And think anything in.

When I read the poetry of Seamus Heaney, I can smell the green fields of my home. His words evoke the sadness of the Northern Irish troubles, the rattle bag of the mother tongue clanging out loud and delightfully clear. I enter into the poem alone and think my own thoughts in.

A poem can transport you and open your mind to a completely different way of life, one entirely different to your own. Poetry can help navigate the dark, by turning on a lightbulb and showing a street where there wasn't one before. It can express something that seems inexpressible, pour balm on grief, toast newlyweds, wet the new baby's head. But poetry can bring something new to the everyday, not just those big occasions.

The recent Carry a Poem city-wide campaign in Edinburgh brought people and poetry together, celebrating the poems that speak directly to our own experiences, showcasing poetry's sheer diversity and the power it has to move, elate, anger, illuminate. It can dazzle you with the tricks it plays with words as well as the sounds it makes when imbibed aloud. It can make you laugh, cry, think. With such a banquet on offer, why not dive in, graze, gulp down something you thought wasn't for you. You might just find yourself surprisingly sated.