A Light in the Darkness III

This week's candle is in answer to Caitlin Ray's request, and I am more than happy to be able to explain this point.

Both "that" and "which" are used to introduce subordinate clauses, and this can lead to a bit of confusion. The difference, however, is simple once explained.

"That" is used for restrictive clauses, and "which" is used for non-restrictive clauses. The easiest way to understand this is to think of "which" as the unnecessary part. The information introduced in a subordinate clause introduced with "which" could be cut from the sentence, and the essential meaning would not change. A subordinate clause introduced by "that", on the other hand, is essential to the meaning of the sentence. Here is an example.

"The coffin that holds the sleeping vampire is right behind you."

But don't worry. It'll take him a while to get out.

In this case the information that the coffin holds a sleeping vampire is of essential importance to the meaning of the sentence. To remove the clause would alter the meaning.

"The giant axe, which was stained with blood, swung down from the ceiling."

It's probably the last thing you saw.

In this case, the information that the axe is stained with blood, though interesting, is not of essential importance. The sentence could read, "The giant axe swung down from the ceiling", and all the essential information would be conveyed.

"Which" clauses are either preceded or set off by commas, as in the above example. "That" clauses are not.

The above is the simplest explanation. There is a bit more information below, but if you find it confusing, ignore it. Stick with the above, and you will be fine.

Now, the restrictive use is not correct if one is trying to restrict the unrestricted. What I mean is if you write a sentence like the following, it might or might not be correct, depending on the situation.

"The dragon that ate your sister is about to eat you."

He ate her because of her poor writing.

This is correct if there is only one dragon that ate your sister. If, however, multiple dragons shared your sister as a meal, then that sentence would not be correct. You would need to write it like this.

"The dragon, which ate your sister, is about to eat you."

The last note is that neither "that" nor "which" are used for people. In both cases, restrictive or non-restrictive, if one is discussing a person, the word is "who".

"The vampire who drained your family is about to drain you."

But she'll leave good writers alone!

"The vampire, who prefers to drink A negative blood, is about to drain you regardless of your blood-type."

If anyone has any further requests, please send them my way. Keep the grammar candles burning!