1. A few things to think about. . .
The Comma
A few things to think about. . .

2. What is it?
In 1582, Richard Mulcaster defined it as “a small crooked point, which in writing followeth some small branch of the sentence, & in reading warneth vs to rest there, & to help our breth a little.”

3. Functions
A separator
It tears about on the hillside of language, endlessly organizing words into sensible groups and making them stay put: sorting and dividing; circling and herding; and of course darting off with a peremptory “woof” to round up any wayward subordinate clause that makes a futile bolt for semantic freedom.

4. A panda walks into a café
A panda walks into a café. He orders a sandwich, eats it, then draws a gun and fires two shots in the air.
“Why?” asks the confused waiter, as the panda makes towards the exit.
The panda produces a badly punctuated wildlife manual and tosses it over his shoulder.

5. “I’m a panda,” he says at the door. “Look it up.”
The waiter turns to the relevant entry and, sure enough, finds an explanation.
“Panda. Large black-and-white bear-like mammal, native to China. Eats, shoots, and leaves.

6. Comma power! “What is this thing called, love?”

7. “Go, get him Surgeons!”
“Go get him, Surgeons!”

8. “Now I must go and get on my lover.”

9. Which love letter would you rather receive?
Dear John,
I want a man who knows what love is all about. You are generous, kind, thoughtful. People who are not like you admit to being inferior. You have ruined me for other men. I yearn for you. I have no feelings when we’re apart. I can be forever happy—will you let me be yours?
Jill
Dear John,
I want a man who knows what love is. All about you are generous, kind, thoughtful people, who are not like you. Admit to being inferior. You have ruined me. For other men I yearn! For you I have no feelings whatsoever. When we’re apart I can be forever happy. Will you let me be?
Yours, Jill

10. It can even change doctrine. . .
“Verily I say unto thee, This day thou shalt be with me in Paradise.”
“Verily I say unto thee this day, Thou shalt be with me in Paradise.”

11. Commas. . .
A courtesy designed to help readers to understand a story without stumbling.
On the page, punctuation performs its grammatical function, but in the mind of the reader it does more than that. It tells the reader how to hum the tune.