Once upon a time, there was a golden-haired princess who lived in a tiny room at the top of a tall tower. She never needed to choose between which or that when she wrote sentences in her diary. This was because she didn’t have many choices at all.

When she was a baby, she was stolen from her parents by a wicked witch, who locked her up in the tower. The witch had told her all about the scary place called Outside, and she hadn’t tried to leave while she was growing up. But now she was a teenager, and getting bored with solitude. She was also getting tired of writing the word which.

***

Dear Diary,

Nothing ever changes around here. The witch has warned me not to leave this place, but I am so bored! The rocking chair, which is over by the fireplace, is still empty.  I want to meet someone! I tried putting my old doll, which has red hair, in the chair to keep me company. But it’s just not the same. When will anything ever happen in this place?

***

The princess used the word which a lot in her diary because most of the things in the tower were unique. She didn’t have to single out a thing from all other things of the same type, so she used the word which to describe them. (Otherwise she would need to use that, which distinguishes between things.)

She didn’t need to write “that doll with the red hair” because she only had one doll. She provided the information that the doll had red hair, but the reader wouldn’t need to know this to identify the doll.

And she didn’t need to write “that rocking chair by the fireplace” because there was only one rocking chair, and it always sat by the fireplace.

Anything described using which is considered “non-essential” information. It can be removed from the sentence without affecting its meaning. (This is why this information is generally placed between commas or parentheses.) The princess could just as easily have written the following:

***

Dear Diary,

Nothing ever changes around here. The witch has warned me not to leave this place, but I am so bored! The rocking chair, which is over by the fireplace, is still empty.  I want to meet someone! I tried putting my old doll, which has red hair, in the chair to keep me company. But it’s just not the same. When will anything ever happen in this place?

***

One day, a handsome prince hacked his way through some vines (ruining his fine sword) and discovered the princess in the tower. He called up to her and told her not to worry—he would find a way to rescue her. She cheerfully yelled down that there was no need. She had figured out how to unlock the tower years ago, and now that something exciting had happened, she was ready to leave. The prince was a bit nonplussed by this, but recovered (and started preening) as he saw her striding towards him with a beaming smile on her face. Maybe it’s a good thing that he didn’t know what she was thinking.

***

Dear Diary,

Today something exciting finally happened. I got to meet a horse! He isn’t like the horse that is in my picture book. He is gleaming white, rather than being black all over. The horse is very nice—not at all like those girl-eating horses that the witch described to me. Oh, and I met a boy, too! He said I could decide which path to take. I was so happy to choose! I asked him, “What’s at the end of the path that follows the river?” He told me it led to his castle. It turns out that he is a prince! Then I asked him, “What’s at the end of the path that goes over the big hill?” He told me there was a town, and they were having a festival today. I’ll bet you can figure out where I went!

***

Our resourceful princess finally got to use that instead of which. She needed her reader to understand that the white horse was not the same as the horse in the book or the horses described by the witch. The reader also needed to know which of the two paths the princess was describing. All of the information is essential, so nothing can be eliminated. (That’s why the information is not surrounded by commas.) Otherwise, we’d have this wonderful nonsense:

***

Dear Diary,

Today something exciting finally happened. I got to meet a horse! He isn’t like the horse that is in my picture book. He is gleaming white, rather than being black all over. The horse is very nice—not at all like those girl-eating horses that the witch described to me. Oh, and I met a boy, too! He said I could decide which path to take. I was so happy to choose! I asked him, “What’s at the end of the path that follows the river?” He told me it led to his castle. It turns out that he is a prince! Then I asked him, “What’s at the end of the path that goes over the big hill?” He told me there was a town, and they were having a festival today. I’ll bet you can figure out where I went!

***

The princess enjoyed her time at the town festival. There were so many activities to choose from.

She danced with many of the townspeople.

(Dear Diary, The boy who had short brown hair danced especially well.)

Then she watched a stage play.

(The sole actress, who played the witch, was not very talented. But I enjoyed it anyway!)

She also fed apples to the magnificent horse.

(I wish I had a horse just like this one!)

***

You can see that the idea of essential vs. non-essential information also applies to the word who. If the information is placed between commas or parentheses, it is non-essential and can be eliminated. (Dear Diary: The sole actress, who played the witch, was not very talented.)

***

Eventually, the prince got bored. He said that it was time to go home to his castle, where he would marry her. She told him that he was crazy—why would she marry him, when she had all of these choices before her? The prince attempted to ride off in a snit, but the horse decided he would rather stay with the princess. So the prince ended up limping home.

THE END (for now – look for more grammar story excitement in future posts!)

P.S. The rules that I describe for which and that are based on North American style guidance. So don’t be surprised if you run into which in a text from England where others would use that. The rules about using commas for non-essential information, however, are still the same. Please feel free to share any of your which (or witch) stories below. Your comments are always welcome!