For the purposes of the following discussion, let's accept for now that poetry is a craft.1 Like all crafts, it has its tool kit and among the tools therein are those dedicated to presentation. Once our ideas have clarified and our words been chosen and ordered, our final duty as poets is, as a minimum, to ensure the reader doesn't get confused or bored stiff by our text, and ideally to render our poem as powerful as possible in conveying its message. Our tools sets for achieving these ends are punctuation and layout.

Of course we're free to do anything we want with presentation (and many of us do – sometimes going to phenomenal lengths) but the human mind being what it is, if we depart too far from what the reader's brain expects, the message we're trying to convey with our words will be buried by their confusion about how to make sense of its presentation. For the moment stepping aside from the school of modern art that puts the entire burden of interpretation on the shoulders of the observer, it's safe to say that, while they're not rules, there are some established basic expectations of punctuation and textual layout that make the reader's life easier and our message clearer.

So let's take a look at how punctuation works, because for many of us its intricacies have become rather hazy. As veteran Times editor Philip Howard pointed out some 40 years ago,2 the variety and subtlety of punctuation have been seriously eroded by 'digitisation' – the dash largely replacing all punctuation marks other than the full stop, question mark and exclamation point. But this is primarily due to the difficulty of spotting small dots on computer screens, not because the change-over improved clarity of expression. Fowler and Fowler's The Kings English 3 (1918) dedicates an entire chapter (some 70 pages) to punctuation, identifying numerous subtle distinctions of meaning resulting from its choice and placement. And surely one of our main goals as poets is to maximise our subtlety of expression, so such distinctions might well be considered useful. However, let's concentrate on the basics.

Full stops terminate the expression of specific ideas. For us as poets they do that and nothing else (unless we resort to abbreviations). Leaving them out makes the reader struggle to work out where each idea starts and ends, which engages the logical left brain in analysis at the expense of the right brain's understanding of our poem. So I suggest that omitting full stops is not a good strategy as it weakens transmission of our message.

Next in line for consideration are commas, which are similar in principle to full stops but on a subordinate level (that is, they provide segmentation within a continuing idea). For example, the statement:

 a sidewalk obstructed by a red pillar box of de-icing salt and iron railings

  at first reading suggests (somewhat incongruously) a red pillar box (a British street letter box) containing the salt and the railings. But the addition of two commas:

 a sidewalk obstructed by a red pillar, box of de-icing salt, and iron railings

 removes any ambiguity. The comma can also be used to suggest emphasis. There's a real if subtle difference between

 He painted the gate bright pink.

 and

 He painted the gate, bright pink.

  in that the first is a bald statement of fact whereas the second suggests surprise or indignation at the colour. There's also an argument that the comma can indicate an inhalation – a brief 'pause for breath' in the flow that's independent of textual emphasis. But this is a tenuous argument potentially leading to commas littered all over the place to little actual effect, as many people don't recognise the comma as functioning in this way and will simply ignore it.

The semicolon ; serves much the same basic separative purpose as the comma, but is slightly stronger in emphasis. It's useful where two clauses containing commas should be separated without ambiguity but still contribute to a single idea. For example:

 the red, green, brown and blue paints were exhausted; the yellow, white and black only half used.

In the absence of the semicolon, we would need two sentences (a full stop following exhausted and an additional were after black), which would result in stronger separation of the two ideas (suggesting, for example, that the two conditions were independent, rather than both together resulting from the painter's immediate activities).

The colon : differs from the comma and semicolon in having the very distinct function of introducing explanation: the statement that follows it clarifies or enlarges on what precedes it (as this sentence demonstrates).

Finally there are brackets ( ). They most often enclose entirely optional subsidiary information that could be omitted without weakening the main argument or rendering it ambiguous. For example:

 the hat he wore (which was green with a black band) had a big feather in it

 But brackets can also indicate a necessary aside – a strictly relevant comment that can't be omitted without weakening the argument but is not the direct thrust of it, as in my poem

Seven years on

The ancient ash tree fell

quietly: its hollow shell,

lately the home of bees,

bereft of its past might.

( They, being wise,

a month before departed

knowing it had died. )

Two centuries it stood

and now it rests

prone, year on year:

a lair for creeping things.

Reluctant to descend at last

into the nettled mold.

 where the second stanza is a necessary aside – a temporary change of subject that's needed to reinforce the argument of the tree's demise. The distinction between these two usages is quite subtle, but they do differ.

I haven't discussed the question mark and exclamation point here in detail as use of the first is mostly self-evident, and the latter should ideally be avoided as far as possible because it's much more effective in poetry to suggest surprise, indignation or excitement (and just about every other emotional response) than to underline it. Suffice to say it has a place in quoted exclamations, as in Coleridge's 4

The naked hulk alongside came,

And the twain were casting dice;

'The game is done! I've won! I've won!'

Quoth she, and whistles thrice.

 but that's about all.

Fowler and Fowler describe numerous subtleties beyond these basics, although most of them have fallen out of common use in the intervening century since they wrote. But substituting the dash for all punctuation except the full stop, question mark and exclamation point eliminates pretty much every remaining clue that aids understanding. The double (before and after) dash has come to substitute for brackets without ambiguity in most cases, and the single dash more or less for the colon. But a quite common poetic habit of entirely eschewing punctuation (even to the extent of using no full stops) only leads to confusion for the reader – who's likely to stop reading.

It may be noted that throughout this note I've repeatedly stressed for the reader, and that's really the key issue. Durable poetry is poetry that gets read by successive generations of people, and it gets read by them because they like it, not because it's hard work to engage with. So of course anyone is at liberty to ignore any of the points made here, derived though they are from study of a long tradition of successful literature, which has relied for that success on empirical understanding of how the reader's brain works. But the question will then be whether as a result, the reader of their poetry will receive the message they intended to transmit with ease or has to struggle for it (or may indeed give up trying).

 [1] Some poets and critics will disagree that poetry's a craft, for example Will Harris in his essay 'Do All Rabbit Hutches Look Alike?' [Rishi Dastidar (ed.), The Craft, Nine Arches Press 2019]. But the definitions of craft that are used by such objectors are typically straw men, and I haven't found any robust alternative definitions of what poetry is supposed to be (only what it's not). Harris, for example, defines 'craft' in terms of parallels such as 'building a wardrobe', arguing that using 'formal features' such as 'evenly spaced vowel sounds' would constitute poetry being a craft (with an inescapable implication that this would somehow be a bad thing).

  I define craft quite differently. A craft is essentially a process of arriving at the capacity to create any product that passes muster in all relevant ways – durability, functionality, convenience, aesthetics et cetera. So how to define a craftsperson? An aspirant has an urge to create, becomes an apprentice, and eventually may rise to mastery. These are the stages of the craft. The aspirant deals solely in ideas, the apprentice gradually develops technique and understanding of tools, materials and potential results by experiment and enquiry, but the master craftsperson knows immediately from experience what is required. The fitness of the final product for its intended purpose and the appropriateness of its materials, techniques of construction and finish (to use Harris' 'wardrobe' analogy) will in the hands of the master craftsperson be optimised intuitively, whereas the apprentice will need to follow rules consciously to achieve any approximation to the same results. If any one or more of the characteristics of the product is less than entirely appropriate, craftsmanship has not been achieved. Consequently, in respect of poetry, Harris' definition is not of a craft but merely of an apprenticeship.

 [2] Philip Howard, The State of the Language, Hamish Hamilton 1984

 [3] H.W. & F.G. Fowler, The Kings's English, Oxford, the Clarendon Press 1918

 [4] Samuel Taylor Coleridge, The Rime of the Ancient Mariner, part 3, stanza 13