From Chemguide:

We'll choose one of these water molecules at random (it doesn't make any difference which one!), and look at the bonding in a bit more detail - showing all the bonds around the oxygen.

Imagine for the moment that the 3+ charge is located entirely on the iron.

Can we change this to "imagine for a moment"? Would there be a significant change in meaning?

Am I right to assume that "for the moment" here means "for the short period of time while we are discussing the issue"? And "for a moment" would mean "for any undeterminate short period of time"?

I did an Ngram search for "imagine for the moment, imagine for a moment", and the latter option seems to be more widespread:


4 Answers 4


There is a difference.

"Imagine for a moment" means any unspecified moment, or a short period of time. This can be any moment. You can choose which moment.

"Imagine for the moment" refers to now. In this case, you are tasked to imagine a thing while reading the argument and to pretend for the sake of the argument that it is true. This is a very specified instant in time.

You can use other examples as well:

Imagine for a moment that the world will end tomorrow - how does this make you feel?

In this case, you can do the imagining in any moment of your choice, and then tell the asker about your thoughts. But in the example of your chemistry book, you need to imagine it for the specific moment in time when reading the argument.

The difference is subtle, but noticeable.

  • 3
    I think this explains it well, but it's strange how when we say, "Imagine for a moment" we usually mean the same thing: "Imagine for a moment right now." We don't usually mean, "Wait some arbitrary length of time, and then start imagining for a moment that..."
    – J.R.
    Commented Apr 20, 2016 at 10:17
  • 4
    Its is not exactly the same. "Imagine for the moment" in this case means "at least as long as it takes for me to make the argument". "Imagine for a moment" could mean that you imagine it, and then start to follow the argument again, because it is not specified which moment is meant. This fits the second example very well - you can reason about your feelings about the end of the world even after you stopped imagining it, but in order to follow the argument, you need to imagine the premisse for the whole length of the argument.
    – Polygnome
    Commented Apr 20, 2016 at 11:12
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    I think there's also a subtle implication with the "the" version that we're going to come back to it and imagine something else for comparison. "Imagine for the moment that the 3+ charge is on the iron... Now assume it's only partially there..."
    – Holloway
    Commented Apr 20, 2016 at 12:12
  • So the original author of the quotation meant "Imagine for now", which refers to when we should imagine it, while "imagine for a moment" would refer to how long we would need to imagine. So there are definite syntactic differences!
    – Mr Lister
    Commented Apr 20, 2016 at 17:07

True. The latter is more common but as I see all the examples for both the strings, I find no great difference in the meaning.

But if I dig in further, I agree with you. '..the moment...' may talk about this very moment when you start thinking whereas 'a', as we all know, talks about any moment when you start thinking.


To my understanding, imagine for a moment is just a variation on the expressions imagine for a minute and imagine for a second. They all mean the exact same thing, but just use slightly different words.

Regarding the example in the text you gave, I asked a friend of mine, who is a native American English speaker, and he said that imagine for the moment sounded absolutely fine to him. I also asked him if there was a difference in meaning between the two expressions and his answer was that he couldn't really see one. So, for the moment and for a moment really do mean the same thing. The only difference that I'm able to see is that for a moment is just used much more commonly. Some like to use the first one, others prefer the second one. That's all there is to it, folks. End of story.

  • 1
    I feel like "imagine for the moment" is an unusual change to the much more commonly uttered "imagine for a moment". In fact, I'd consider the former to mean the latter, and assume the person is saying it wrong. (Australian English speaker here, in case that makes a difference)
    – Tim Malone
    Commented Apr 20, 2016 at 8:02

I think "for the moment" is used because the "moment" here refers to "the moment you're looking at the bonding in a bit more detail." Your understanding about "for the moment" and "for a moment" should be correct.

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