1 There is the most important thing which you must know.

2 There is a most important thing which you must know.

I think 1 can't be correct. How else can it be conveyed? 2 means "a very important" hence doesn't mean "the most important".

  • 2
    "The most important thing, which you must know, is that..." Jan 7, 2023 at 10:19
  • What if I don't want to say what this thing is. Your version prompts the speaker to mention this thing.
    – user1425
    Jan 7, 2023 at 10:36
  • 1
    That doesn't make sense. How can you tell someone they 'must know' something if you can't say what it is? Jan 7, 2023 at 10:44
  • It makes perfect sense. I want to say that there is a thing which someone must know. But I want this person to ask me what I mean. If there wasn't the word "MOST" it would be easy. "There is a thing which you must know." but it doesn't work with "There is the most important thing which you must know"
    – user1425
    Jan 7, 2023 at 10:57
  • Perhaps you want to say "It's most important that you know this thing". The problem with your examples is that "There is" doesn't work here. We use "There is" to point to the existence of something. For example "There is a dog". It sounds strange in your example. It's like you are saying "A most important thing exists" which is a little odd. I mean it's understandable, but not generally the way we would express something like this.
    – Billy Kerr
    Jan 7, 2023 at 13:19

3 Answers 3


A sentence beginning with There is usually announces the existence of something.

There is someone asking for you on the phone.

There is a fly in my soup.

As you know, the definite article usually refers to something that the hearer already knows about.

I'm going to wash the dishes (from the meal we've just had).

I live near the park.

That's why it sounds odd to say There is the thing (unless you are pointing it out, which is a different sense of there is.)

  • I found this in a newspaper. It has "there is the". Why? "There's all that, and then there's the most important thing to consider when debunking this falsehood — the Beatles wouldn't have been the Beatles without Ringo."
    – user1425
    Jan 7, 2023 at 12:40
  • 2
    Notre that both Astralbee and I said 'it sounds odd', not 'it is never used'. I don't know why the journalist wrote it that way, except that it's shorter than there's another thing which is the most important one to consider... Jan 7, 2023 at 13:20

When used as an adverb of degree, 'most' has two uses. Webster's dictionary gives these two definitions:

  • to the greatest or highest degree
  • to a very great degree

So it can mean the highest, or just very high. It should be easy to spot the difference in use because when something is the highest it is also one unique thing and would have the definite article, for example:

  • the film was the most enjoyable
  • the film was most enjoyable

With your example, you could certainly speak of "the most important thing", which would mean the thing of the absolute highest importance among other things. Still, you could also say "a most important thing" to refer to any very important thing.

That said, your example just doesn't sound quite right, at least not without any context. It sounds very much like an opening statement, but if there is one thing that is the most important then there must be other, less important things, and your audience must know about them otherwise you wouldn't be using this superlative. So it just sounds odd to have this grand opening statement about the most important thing if other things have already been discussed.

  • OK. Thank you. I am still not clear on the status of the sentence. Is it grammatically wrong or doesn't sound quite right? What about these: There is the most important man in the world. There is no most important man in the world. Is there the most important man in the world?
    – user1425
    Jan 7, 2023 at 11:24
  • 1
    @user1425 It doesn't sound idiomatic, sorry. But maybe the context (the surrounding text) may correct that. Are you pointing at the most important man and saying "there it is"? We don't really do proof-reading here, that is off-topic.
    – Astralbee
    Jan 7, 2023 at 11:29
  • But it's not about proof-reading. It's about the usage of "the" with "there is". It's a grammar topic. I am not pointing at the person. I am saying that "The most important person exists" in the world.
    – user1425
    Jan 7, 2023 at 11:32
  • @user1425 I meant that if you provided a block of text and asked if it was right, that would be proof-reading, so understandably we don't have the context. To what you're saying now - doesn't that go without saying? At any given moment, someone in the world is the most important man. If that person didn't exist, it would be someone else. Surely there is more to that statement?
    – Astralbee
    Jan 7, 2023 at 11:41
  • 1
    How about replacing 'most important' with 'vital' ? 'A..' or 'The most important thing' can both be technically correct, but either one invites all sorts of possible misinterpretations. For instance: unless you had no things, or a tie, there must be one 'most important thing' but that thing might not be very important. I cannot point to any particular error, but the sentence is not a happy one. Jan 7, 2023 at 12:03

Starting with 'there is the/a' doesn't really function well, no matter where you are heading with the overall sentence. You could get away with "There is one important thing", which at least then matches count, far better than "there is a" even though the two may be numerically equivalent, the ideas presented are different.
However, "There is one most important…" doesn't work. One is always the most important. There's only one, so there is no hierarchy of importance, unless this is the culmination of a list of important things we don't know about.
If you were using this as dialog to increase tension, then brevity, getting to the point, works better.

What you seem to be aiming towards, judging from the many comments, is a sentence which will be left dangling, forcing the listener to complete it for you.

The most important thing, you must know…

demands the listener to say at least


thereby leaving you to finish with a flourish

that we keep aliens in the basement!

These are all partial sentences, which would only really work in colloquial speech or as dialog in a novel. None of them truly can stand alone.

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