What could a left-handed comma possibly be? Is there a right-handed comma? It took some digging, but there is such a thing, or perhaps “designation” is a better word.
Commas are always in pairs, a left and right one. The trouble is, they both look the same, and their use would be clearer for both reader and writer if they were different, as we do with parentheses. An easy solution would be to reverse the direction of the left comma to face inward.
The pair, as in this sentence, is often obvious. Both are visible unless one of the pair coincides with another punctuation mark that takes precedence. Often the right side of the pair is subsumed into the period at the end of the sentence, as this one. At the beginning of a sentence, the left side is subsumed into the capitalization (as in this sentence). But they still exist as a pair, visible or not.
Lists also use commas in pairs for all items after the first, although the right-hand comma often gets subsumed into the left-hand comma of the following item. “We have four kinds of pizza: mushroom, olive, pepper, and onion.” “Olive” and “pepper” share the same comma. In scientific writing, we were always taught to keep the comma before the final “and” for clarity. Without that comma, suppose the sentence were “We have four kinds of pizza: tuna, mushroom, olive and pepper and onion.” How would you know whether the third kind was olive and pepper or the fourth kind was pepper and onion?
The comma was invented in Byzantium in the Third Century, BC, to indicate a breath when reciting poetry. They used three dots arranged vertically for a full breath. Just one dot in the middle indicated a slight pause for a short passage called a “komma.” Eventually, the word came to mean the mark itself rather than the passage. Later, in the Middle Ages, the comma was indicated by a slash that deteriorated into the tailed-period we use today and explains why the tail faces the direction it does.
Chinese did not use punctuation at all until the early 1900s when they adopted it from Western writing. But they are not comfortable with it. Chinese poetry still does not use punctuation, and punctuation mistakes are often typical of the translated Chinese we get in our owner’s manuals.
Parenthesis come in pairs, quotation marks come in pairs, and so do commas, so why not always use both and face them in opposite directions to tell them apart? And do not subsume them. It would help clarify the sentence structure.
Okay, I understand this is pretty radical and will never happen. If it were really useful, it would have evolved naturally centuries ago. But just thinking of commas as pairs may help you as both a reader and writer.