I need to start a sentence by saying that something has been known for a long time. What is the most elegant way of writing that? Two possibilities that come to my mind are:

1) It has been known since long time that ...

2) Since long, it has been known that ...

Personally, I prefer the second option. The first sounds ugly to me. But since I'm not a native English speaker, I would like to ask for suggestions of what would be the best way of saying that. Please feel free to suggest other forms.

  • 3
    You cannot use "for" and "since" interchangeably. Something is know ''for some period of time'' or ''since some specific point in time''. So while your introductionary paragraph (for a long time) is correct, both options 1) and 2) are flawed. Possible solutions include replacing ''since'' with ''for'' or starting with something like: ''Since long ago, it has been known that ...'
    – inVader
    Commented Aug 14, 2015 at 14:34
  • I think the question is not about whether to use 'for' or 'since', he just got that wrong not being a native speaker and maybe it should just be edited in the question. I think it's about word order which ultimately comes down to what part should be emphasized.
    – inVader
    Commented Aug 14, 2015 at 14:49
  • Some languages, like French (depuis) and German (seit) and probably others, have words which are usually translated as since but also entail entirely different constructions around them. As this question stands, it would appear to be concerned with the construction around since -- as "for a long time" appears in the question, quite correctly. Commented Aug 14, 2015 at 15:33
  • Neither of OP's versions are idiomatically acceptable (they're reminiscent of the ungrammatical Me love you long time, as popularized by the movie Full Metal Jacket and now often used mockingly). But I should have cited this question as the duplicate. Commented Aug 14, 2015 at 16:07

3 Answers 3


My suggestion on how to improve the wording:

1) It has long been known that ...

2) Since time immemorial, it has been known that ...


I would say it depends on what you want to convey to the reader.

The second option definately puts more emphasis on the long timespan by starting of the sentence with ''For long, ...''. So if it is really important to you or the reader that it is not only known but known for an extended period of time (maybe talking about ancient knowledge or something), this is probably the better choice. In that case, however, you might also want to consider being more precise conceirning the timespan:

Since ancient times/ the middle-ages, ...

For centuries/ages/, ...

If it is just about the knowledge and the ''long time''-part is merely some additional but minor information for the reader, ''It has been known for a long time ...'' might be a more adequate choice.

But really, the differences are subtle and both options could be just fine in your case.

There are similar cases where the word order defines emphasis, for example:

In chapter 2, we have shown that ...


We have shown in chapter 2 that ...

  • It wouldn't be a bad idea to combine your answer and your comment, since they could become detached (or lost) and the one needs the other, to make sense.
    – Margana
    Commented Aug 14, 2015 at 14:47
  • I think it would be better to edit the question, eliminating the misuse of 'since' in favor of 'for'. I did that, too, but it's pending approval.
    – inVader
    Commented Aug 14, 2015 at 14:52

The preposition since must take as its object a noun or nominal naming a point in time: the starting point for the timespan you are defining.


  • You cannot say "since long", because long is an adjective, not a nominal.

  • You cannot say "since long time", because long time (or short time, or some time) by itself (or with an article) designates a timespan, not a point in time.

What you want to say is either

  • "for a long time" — for takes a timespan as its object


  • "since a long time ago" — ago 'recategorizes' time as a point in time. It's a very vague, unspecific point, a "fuzzy" point, but it's a point.

It doesn't really matter whether you say "It has been known for a long time" or "For a long time it has been known". The version with the main clause first is more colloquial, while the version with the temporal first has a distinctly literary ring, and I would use the colloquial version; but that's just my taste.