Not … until

My class stumped me today with a GMAT sentence correction question involving not … until. I ended up delving into the Cambridge Grammar of the English Language, and here is my tentative explanation:

Until marks the “endpoint” of an action or state, and it can be a preposition or conjunction:

(1) I played the piano until I was 12 years ago.
(=I stopped playing the piano when I was 12; you don’t know when I started.

(2) The cafeteria is open until 6pm.
(=The cafeteria closes at 6pm.)

It is not easy to move until 6pm to theĀ  front of sentence (2) (?”from 6pm, the cafeteria is open”) because until 6pm completes the meaning of is open, and so has to come after it. To put it another way, until 6pm is an adverbial expression of time that modifies “is open”, not the entire sentence, so it needs to come after the verb.

However, when the clause is negative, the meaning is more complex. Here is the example from CGEL:

(3) I didn’t notice my error until later.
(=I only noticed my error later)

There is no positive version of this sentence (*”I noticed my error until later” is ungrammatical). The adverbial until later tells us “how long this negative state of affairs lasted.” That is, not … until tells us when something started happening. You can’t move it to the start of the sentence because is modifies the verb, by telling us when the negative (didn’t notice) stopped being true.

So, in the class example from the GMAT practice book (I’m paraphrasing):

(4) Scholars did not begin to study Native American poetry until 1900.
(=Scholars began studying Native American poetry in 1900.)

Since the adverbial (since 1900) is part of the verb “did not begin”, it cannot simply be moved to the start of the sentence. (On the other hand, we can say: After 1900, scholars began studying poetry because “after 1900” modifies the entire clause.)

However, it is possible to move any element to the front using an it cleft. The negative (not) needs to move with until because they create the meaning of a starting point together:

(5) It was not until 1900 that scholars began studying …

Please post questions or other examples!

Reference: Huddleston & Pullum, Cambridge Grammar of the English Language (Cambridge University Press, 2002).