Grammar: Clause: Using the clause to organise text

Further reading

Cleft sentences

The typical or 'unmarked' way of making a Statement is to put the Subject in Theme position; however, sometimes we want to focus even more closely on something, so we use a special structure such as It is.

It was my cat, Felix, that caught a butterfly.

This has the effect of emphasising one noun group (in this case my cat, Felix). We could have said My cat Felix caught a butterfly and the focus would still be on my cat, Felix; however, the use of the structure it was (technically a 'cleft sentence') makes the focus even more pronounced.

Cleft sentences are particularly useful if you want to correct someone's misapprehension, or say something in contrast to something else. Note where the stress falls in these cases:

Was it your dog, Fido, that caught a butterfly?
No, it was my cat, Felix, that caught one. 

Was it Boris the Cat who went to sleep for a while?
No, it was Boris the Bat.

Again, we can analyse individual clauses:

However, because this is a sentence (or clause complex) the clause that comes first can be interpreted as the Theme of the whole sentence:

Note that the terms New Information and Theme are written with a capital to remind us that they are functional terms.