The Guardian (4-9-2014)

Despite claims to the contrary Peter Carey did not get rid of all the commas in his 2001 Booker prize-winning novel True History of the Kelly Gang (there are 13 on the first page alone) and attempting to write without them is a pretty bad idea in general because as you can see you are likely to end up with very long unwieldy sentences like this one that are difficult to read and leave your poor readers out of breath well before they get to the end.

A comma helps the reader by inserting breathing space into a sentence, making it easier to read, like this one. Using a comma wrongly, as in this sentence is very irritating.

To help develop an instinctive feel for the flow of a sentence, try reading it aloud and insert a comma when you pause (as I just did after the word “sentence”). If you use commas as parentheses, to explain something or add extra information as I am doing here, make sure you add the second comma just as you would add a second bracket. So the second sentence of the headline above should read “How to use, and not use, the comma.”

Commas have lots of other uses. A misplaced one might even be damaging to your health. Compare “Do not administer any liquids which are diuretic” (some liquids are permissible) and “Do not administer any liquids, which are diuretic” (all liquids are forbidden).

If you could use “and” between adjectives in a list, use a comma: a bright red car doesn’t need one because you wouldn’t say “a bright and red car”; a tall, dark, handsome man does, because you could say “tall and dark and handsome”. This example from the Guardian shows how a misplaced comma in such a list can actually sabotage the intended meaning: “Neocon economists often claim a large, black economy turbo-powers growth.” The writer meant a large black economy, not a large and black one, which is what this says.

You can use a comma to introduce a quote, “He said,” although I prefer a colon: “He added.”

A comma can also change the general to the specific. Note these two sentences:

“The author David Marsh says this is more interesting than many grammar books.”

“The author, David Marsh, says this is more interesting than many grammar books.”

In the first example, David Marsh is an author in general; in the second, he is specifically identified as the author of this book. It is interchangeable with “David Marsh, the author, says … ” whereas in the first example “David Marsh the author says” sounds a little unnatural, unless it’s to differentiate him from all the other David Marshes.

A comma splice, which sounds painful, occurs when a comma is not up to the job of joining two clauses: “This was sensible advice, it was almost too easy” would be improved by using a semicolon or a conjunction such as “but” instead of the comma.

Commas are crucially important in relative clauses. To see how to get it wrong, consider this example from the Guardian: “Part of the report will heavily criticise a so-called power culture among the Dublin bishops who have been accused of not taking the allegations seriously.”

As written, the words beginning “who have been accused” comprise a restrictive relative clause: it says only some Dublin bishops have been accused. The writer in fact meant to say all of the bishops had been accused, so needed to insert a comma after “bishops” to introduce a non-restrictive relative clause:

“Part of the report will heavily criticise a so-called power culture among the Dublin bishops, who have been accused of not taking the allegations seriously.”

Looking at the sentence now with the relative clause removed: “Part of the report will heavily criticise a so-called power culture among the Dublin bishops” you can see this still conveys the desired meaning that all the Dublin bishops and their so-called power culture have been criticised.

So if you add a relative clause giving additional, non-essential information, you must introduce it with a comma. You wouldn’t think such a simple thing could completely change the meaning, but it can and does all the time, which is why understanding how commas work is so important.

Keith Waterhouse advised: “Commas are not condiments. Do not pepper sentences with them unnecessarily.” Quite so, but a well-placed one is the difference between “what is this thing called love?” and “what is this thing called, love?” And between “let’s eat, Grandma!” and … well, you know the rest.