Commas as Parentheses

You can use commas like parentheses, wrapping around a word or phrase or clause inside a sentence - provided that the word or phrase or clause is something extra, something that is not essential to the meaning of the sentence. Here are some examples:

• The "Judgment of Paris," a scene depicted in many paintings, shows Paris choosing between three goddesses: Hera, Athena, and Aphrodite.
• Paris, who was a prince of Troy, must decide which of the goddesses is the most beautiful.
• Each of the goddesses, convinced of her own great beauty, offers to give Paris a reward in order to win the contest.
• Paris, unable to resist Aphrodite's offer, declares that she is the most beautiful.
• His prize is Queen Helen of Sparta, the wife of King Menelaus, and she is known forever after as "Helen of Troy."
• Paris, however, will come to regret these events because they lead to the Trojan War and the utter destruction of the Trojans as a people.

To determine whether the word or phrase or clauses is essential, you can ask yourself some questions:

• If you leave the word/phrase/clause out, does the sentence still make sense?
• Is there a kind of "bump" or "pause" in the flow of the sentence because of the word/phrase/clause?
• Can you safely move the word/phrase/clause somewhere else in the sentence without changing its meaning?

If you answer "yes" to one or more of these questions, then the element in question is nonessential and should be set off with commas. See also the page about essential and non-essential relative clauses.

---

To find out more about the three goddesses vying for the favor of Paris, see Wikipedia.

(image source)