I found this phrase in my biology textbook (emphasis added):

...in relation to Earth's history, 100,000 years or even a million years is the blink of an eye.

The part of the phrase in question is the word "the" in italics. In this context, doesn't it make more sense to use the indefinite article "a" instead of the definite article "the", since there can be more than one "blink of an eye"? Is "a blink of an eye" incorrect in this context? Are idioms like this exceptions to normal definite and indefinite article usage, even though the literal meaning of the idiom makes better sense otherwise?

  • By the way, this has turned out to be a good question, imo, and I'd vote it up if I could, but I'm not yet able to register here properly, for some unknown reason, so I'm adding this in lieu of an up vote. Dec 2, 2011 at 20:23

5 Answers 5


As has been pointed out, the overwhelming form of the idiom is the blink of an eye. So there's no issue of correctness involved. The questioner, however, had some specific questions that deserve attention, since they suggest some underlying grammatical misunderstandings. Specifically,

In this context, doesn't it make more sense to use the indefinite article "a" instead of the definite article "the", since there can be more than one "blink of an eye"?

This is not a function of the definite article in many situations. For instance,

  • We dialed the wrong number,
  • *We dialed a wrong number

even though there is only one right number, and millions of wrong ones, the idiom is always the wrong number. It's natural to native speakers, and always surprises us when we first notice it.

Articles, like other syntactic particles, don't really have any dependable meaning; they're just a convenient set of labels to attach to just about any set of things we might want to distinguish from one another. They have lots of syntactic functions, though: for instance, a predicate count noun has to have an article, as well as some form of be:

  • This is copper. (predicate mass noun)
  • He is a doctor. (predicate count noun)
  • *He is doctor.
  • He is the doctor.

Only the first two sentences above are predicate noun constructions. The third is ungrammatical; and the fourth is an equative construction, with the doctor referring to some previously mentioned doctor (or, alternatively, to some social role he is acting out), but not necessarily predicating Doctorhood of him.

Is "a blink of an eye" incorrect in this context?

No, it's just rare. This question's been answered.

However, one should be careful about using the term "correct" in talking about grammar, especially English grammar, which is mostly syntax, and most especially when dealing with syntactic phenomena like articles.

Most ideas about "correctness" (and those are scare quotes) come from vague generalizations, while a great deal of fact is actually known about article usage in English. There are dozens of special uses for articles -- an applied linguist once told me he'd counted more than sixty -- and they mostly don't make much sense at all.

Why, for instance, is it The University of Michigan and not *The Michigan State University? Or The Missouri River and The Nile River, but not *The Lake Superior or *The Loon Lake?

Are idioms like this exceptions to normal definite and indefinite article usage, even though the literal meaning of the idiom makes better sense otherwise?

No, not really. There is no "normal definite and indefinite article usage" in terms of "making sense", which is a semantic concept involving meaning, not a syntactic concept involving grammar. Grammar has nothing to do with making sense; grammar has to do with constructions and how they are used.

Moral: Don't confuse names with descriptions. What's called "the definite article" isn't necessarily more "definite" (and note what a slippery concept that is :-) than anything else; it's just one more syntactic marker, like the to that marks an infinitive, or the to that marks the direct object of listen, and it's no more meaningful by itself.

  • 1
    Why can't we dial a wrong number?
    – Unreason
    Dec 2, 2011 at 18:35
  • 1
    Fascinating! Like most people (and true to my monicker!) I usually dialed the wrong number. But if I got lost en route somewhere, I took a wrong turn - again, same as most people. Dec 2, 2011 at 19:43
  • If I receive such a call, I'd tell the person calling me, "You have the wrong number." but to the person standing next to me I'd say, "It was a wrong number." Interesting...
    – Pitarou
    Apr 30, 2012 at 3:55
  • 1
    I also was surprised that we always deal THE wrong number. Maybe somebody even knows that number?
    – Anixx
    Apr 30, 2012 at 4:27
  • I believe blink of an eye is new, and that it historically was always wink of an eye.
    – tchrist
    Oct 1, 2012 at 1:50

Both idioms,

a blink of an eye.


the blink of an eye.

are reasonable alternatives.

To be logical, which is somewhat contrary to the spirit of an idiom, both refer to the indeterminate 'an eye'. So whether you refer to the determined 'blink' of that undetermined eye, or some indeterminate blink, it is still indeterminate (because you don't know whose eye it is.

Google nGrams shows that 'the' much more popular than 'an':

enter image description here

So the direct answer to your question is yes, idioms can follow whatever rules they feel like, and so can display 'exceptions' to strict grammar.

  • @FumbleFingers: hmm...I was blind to the actual data. I wrote what I expected rather than what the data actually said. Changed to be closer to reality.
    – Mitch
    Dec 2, 2011 at 15:37
  • @FumbleFingers: 'the' sounds wrong to me, but that could easily be anchored by the question itself. But evidence is to the contrary.
    – Mitch
    Dec 2, 2011 at 15:41
  • When I first read the question I didn't have any strong feeling about "the" being "better", or "more common" in the general sense. I just thought it was better in OP's specific phrasing because otherwise you'd have three indefinite articles in close proximity, all playing slightly different syntactic roles. I might graph the other two permutations (a + the, the + the) - I'd expect both of them to be less common, particularly the latter. Dec 2, 2011 at 16:08
  • 1
    This idiom is usually used as in the blink of an eye. Because the phrase blink of an eye (with a form of the verb "be" instead, as in is the blink of an eye) is used instead of the full idiom, this didn't seem to make sense to me.
    – bwDraco
    Dec 2, 2011 at 17:04

What we have here is an instance of the use of the definite article used for generic reference. In the words of the ‘Longman Student Grammar of Spoken and Written English’,

Reference is generic when a noun phrase refers to the whole class, rather than just one or more instances of the class. In English all three articles (a/an, the and zero) can be used for generic reference.

  • It's hard to say what's generic and what's not when one is referring to a metaphoric blink of a metaphoric eye. There are Definite and Indefinite Generic constructions, to be sure, but they're not easy to recognize without syntactic tests. Dec 2, 2011 at 19:32

As Mitch's chart makes clear, "the" is much more common than "a" in this construction. But there's nothing grammatically or logically "right" or "wrong" about either form, and "a" is far from unknown.

I think the preference for "the" is simply because most people feel it's "awkward" to use two indefinite articles in the same "set phrase" - even more so in OP's example, where there's another one in a million years just before it.

But even though we seem to prefer having at least one definite article in the expression, it's pretty clear not many of us like using "the" in both positions - (the red line right at the bottom here...)


I was quite intrigued by the comments made by Pitarou, in the question regarding why we say to the caller "You called the wrong number", but we say "it was a wrong number" to the person next to you.

  • In the first case, you are basically saying to the caller "you think you called the right number but actually you dialed the wrong number" to emphasize that it was not the right one. This is all summed up in the short sentence "you called the wrong number" without spelling out everything.

  • In the second case, you are saying to the person next to you, "among many calls we get, that one was a wrong one".

So there is some subtle difference here, but we do these sorts of things so many times, it has become like a "habit" — that is, we summarize in short sentences, without making lengthy, obvious points.

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