There's an old Afghan joke about the villager who was nicknamed 'two brains'. A visitor assumed that meant he was the village smart guy, until he was told that the local word for a walnut meant 'four brains'.

But that's actually rather unkind, as all of us broadly speaking have two brains – a left hemisphere controlling the right side nervous system and dealing with language, analysis and (at least for right handed people) motor control for physical tasks such as writing; and a right hemisphere controlling the left side nervous system and primarily dealing with such things as spatial awareness, interpretation of meaning, metaphor, humour and emotions.

In terms of thought processes this can be summarised as left brain activity – logical, sequential, analytical (plodding), and right brain activity – simultaneous, holistic, synthetic (flying).

This is of course a very superficial summary, and I use the word 'primarily' because the division is not absolutely watertight and can differ for left handed people and those who've lost and then re-acquired capacities, for example in recovery after head injury. However without question such a division of mental processes exists, so when I use the terms 'left brain' and 'right brain' here, it's to distinguish between the mental process sets that result in plodding and flying, regardless of how they may be topologically distributed in any given physical brain.

Why is this of interest to us as poets? Firstly, it clarifies the distinction between the writing of rhetoric and poetry. Rhetoric is an entirely left brain activity – logical, sequential presentation of an argument according to set rules. The thinking and physical process of writing (or typing) reside side by side in the left brain. So it's easy, having once learned the rules, to plod out rhetoric by the ream. On the other hand, intuitive (often called 'inspired') poetry starts in the right brain as concepts (flying) and must be communicated to the left in order to be converted into language and structures (plodding). So in a sense, every such poem is a translation.

Secondly, supposing an idea for a poem has emerged, we should consider how these two disparate mental process sets interact – the extent to which each dominates the overall process of creation, and the sequence in which they are engaged. The more the left (plodding) brain takes over overall command, the more 'ordinary' the results are likely to be, as logic and sequence, although necessary for clarity of communication, are no substitutes for metaphor, allusion and emotional emphasis. And as to the sequence with which the two types of activity are employed, if the left (plodding) brain is engaged first it will probably prevent the right brain flying at all, by taking total rational command.

So if you're content to produce rhetoric, don't worry about any of this too much, because education in our Western intellectual culture emphasises plodding at the expense of flying anyway. And you'll be in good company – the vast majority of non-prose output from the couple of centuries up the middle of the 19th was rhetoric, and much of what has survived is really high quality of its kind.

But if you want to write truly original poetry born of personal inspiration you must let your right brain fly at every opportunity that presents itself, remembering however that it's impossible to force take-offs to occur.