I have it on good authority that some teachers of English have taught students to “put in a comma when you think you need to take a breath”.
In my darker moments, I think: “come the revolution, they’ll be first up against the wall.”
In fairness to those whom I think should go up against the wall, they must fall into one of two categories: those who unthinkingly follow the herd (or heard) and those who have the benefit of too much intellect and a classical education.
Let’s be clear: in the phase space of all of possible rules applicable to the use of the comma in English, breathing isn’t present. A comma is another one of those typesetters’ marks intended to break long-winded ideas up into manageable units of meaning. It’s an aid to comprehension, not breathing.
Now, old Greek dots and dithers are a different story. You might like to chase up the system invented by Aristophanes of Byzantium in the third century BCE, where several dots did indeed mean “you’ll need this amount of breath to finish the verse.” I presume this is the origin of the comma calumny in English, given that the symbiotic relationships in Europe between the classical languages and the local vernacular meant that rules of punctuation everywhere were made up on the spot, hotly debated and personally endorsed or not by the literati of the day. All punctuation was still evolving even in the intellectual heyday of the seventeenth and eighteenth centuries.
Punctuation generally is vitally important in English in a way that was not true for classical Latin and Greek. The vital difference between English and those classical languages is that words in the classical languages carry clues as to their function and relationship to the words immediately surrounding them: they are inflected languages. Their grammar is self-evident on a word-by-word basis and the scope of the sentence is pretty much unambiguous as a result. The word’s inflections get changed on an as-need basis and new, periodised (ie has a beginning and an end) groupings take shape as a result.
English, on the other hand, has a simplified grammar which relies on word order to function correctly. Words tend to retain their shape once they have a job to do.
Rules for punctuation in English evolved especially after the Reformation in England (1536- c.1590) settled in and English became a political weapon against the world. You’d think that scholars would be at the forefront of this, but in truth they were always fighting a rearguard action against the new kids on the block, the printers. Printers had jobs to do and money to make and lead and antimony were expensive, so they just invented, cut costs and compromised.
Reading the texts of the day it is clear that the printers tried very hard in several ways to get the printed word to replicate the spoken word. The idea of one idea = one sentence is common enough today, but it still isn’t quite how we speak. We spill our minds in a stream to our audience. How on earth could printers arrange that stream so that a reader, who of course could not always make sense of it by reading aloud, could comprehend the ideas?
Enter the comma.
It seems that the origin of the physical comma shape is the simple vertical slash, which for stylistic reasons was allowed to incline forward [/] and suffered names such as virgule or solidus. It served multiple purposes in mediaeval scripts. The [/] may be regarded as the ancestor of the comma, the full stop or period mark, various flavours of available brackets and possibly the apostrophe. It must’ve been the Swiss Army knife of punctuation in its time, and still has a modern and vigorous life in computer file addresses and programming languages today.
The comma has settled down to a kind of structured existence, although modern, more liberal, grammarians still argue about whether commas are subject to rules or better looked on as a vehicle for one’s personal expressive ingenuity (Spike Milligan was brilliant at this: his book editors clearly gave up the struggle to regularise Spike’s commas very early in their process). You can check the conventions (a lovely weasel word) on the Internet yourself, if you wish, or elsewhere on this site.*
It takes time and some thought to truly appreciate the wayward nature of the comma: a waif, a stray which, even today, we haven’t really house-trained.
Down, Comma. Good Comma… Sit.*Have a look at Commas, a how-to for a little more about the rules/ conventions for the comma.