# Mathematical forms in poetry 1: the Fibonacci poem

The house in Aberdeen where we used to live had a large garden surrounded by woodland and fields. My initial enthusiasm for filling the borders with pretty flowering plants was soon tempered by the fact that the garden was a happy feeding ground for rabbits. They bred like their proverbial namesakes – in a matter of months, one or two fluffy little bunnies gambolling sweetly at the bottom of the lawn became a dozen or more, brazenly nibbling my roses and petunias.

Perhaps the 13th century mathematician Leonardo Pisano also had pesky rabbits demolishing his plants, for in his book Liber Abaci, published in 1202, he posed the following problem: Suppose there are two baby rabbits in a walled field, one male and one female. After one month they are mature enough to breed, and consequently at the end of the following month they produce a baby pair of their own, again one male and one female. Assuming the rabbits continue to reproduce in the same way, how many pairs of rabbits will be in the field after one year?

The sequence so generated crops up in many different contexts in both nature and mathematics. We know it as the Fibonacci sequence (Fibonacci was Pisano’s nickname), although it appeared centuries earlier in India in connection with studies of Sanskrit poetic metre. And, delightfully, it has inspired an experimental form in contemporary Western poetry –  the Fib poem, which has a structure based on the Fibonacci sequence.

In their fascinating book Discovering Patterns in Mathematics and Poetry, Marcia Birken and Anne Coon discuss the appearance of the Fibonacci sequence in Western poetry from Virgil to modern times. However, it was not until 2006 that the Fib poem gained widespread popularity following a blog post by Gregory Pincus that went, as we would say nowadays, viral. Pincus defined a Fib poem as ‘a six line, 20 syllable poem with a syllable count by line of 1/1/2/3/5/8 – the classic Fibonacci sequence.’

My own introduction to the Fib poem was via JoAnne Growney’s wonderful blog, Intersections – Poetry with Mathematics, the go-to site for everything related to mathematical poetry.

Here’s a little, off-the-cuff example of a Fib poem:

```I
like
playing
with patterns
in crochet, music,
poetry and mathematics.```

As a simple, fun and engaging interface between poetry and mathematics, Fib poems are a wonderful teaching tool. Part of their charm lies in their accessibility: the intrinsic pattern is easy to understand and, as you can see from my effort above, it doesn’t require much verbal dexterity to match words to the syllable count. However, the form’s possibilities extend well beyond the straightforward six-line version. ‘On the way to New Jersey in winter of 2000’ by Sarah Glaz is a 12-line Fibonacci poem, with 144 syllables in the final line. (You can listen to Sarah Glaz reading this fine poem, together with some of her other poetry, here).

A browse around recent issues of the Fib Review, an online publication dedicated to Fib poetry, will provide many stunning illustrations of the form’s versatility. The growth and/or decay in line lengths can allow for creative use of space and shape on the page. Consider, for example, Colin Bell’s poem ‘Pandemic’, with its skilful employment of ascending and descending cadence, Tyson West’s ‘Covid Curls’ or Dan May’s deftly humorous ‘Would-Be Exam Fibs’ which is laid out as the multi-choice exam question from hell.

The structure of a Fib poem need not be defined by the number of syllables per line. My poem  ‘Pathways’ depends on a letter count per line (with the additional constraint that the letters in each word add up to a Fibonacci number).  A.E. Weisberger’s experimental, powerfully visual poem ‘Mary-Pat’ uses a space and character count. And in ‘the irrational’ Roberto Christiano applies a word count, musing that

```‘not everything can
explain the
multiplying
rabbits’```

Which brings us back to Pisano’s highly implausible problem that, centuries later, would provide the inspiration for a fun, versatile and innovative poetic form. Perhaps rabbits in a garden are good for something after all.