By using a comma or leaving it out, you can change the meaning of a sentence. In one case, a comma can make you a cannibal. What is the difference between these two sentences?
Let’s eat, Grandma.
Let’s eat Grandma.
In the first sentence, with a comma, you are telling Grandma that you want to eat. In the second sentence, without the comma, you are stating that you want to eat Grandma!
Why does the absence of a comma make you a cannibal? To answer this question, we need to understand what commas do. Commas separate elements in sentences. When you add a comma, you indicate that parts of sentences are not connected. When you leave them out, you indicate that parts are connected. We see this in our sample sentences.
With Comma: The first sentence, with a comma, separates Grandma from eat. The comma makes Grandma a separate element in the sentence, not connected to the words immediately before. It indicates that Grandma is not the direct object of the verb eat, meaning the action of eating is not done to Grandma. You are not a cannibal.
Without Comma: The second sentence, without the comma, joins Grandma and eat. This indicates that Grandma is the direct object of the verb eat, meaning the action of eating is done to Grandma. You are a cannibal.
The first sentence also follows Zen Comma rule M: When directly addressing someone [writing to a person and using that person’s name], place commas around his or her name. This advice from Zen Comma is based on the purpose of commas. The commas around a person’s name separate that element (the name) from the rest of the sentence to show that it provides a new and complete piece of information.
Commas around a person’s name also prevent you from becoming a cannibal.
Need help with commas? Get Zen Comma, an instructive reference guide on the 17 major uses and misuses of commas, available in PDF and Kindle formats. Read more about Zen Comma.