idiomsphrasesproverbs
I know lyrics meaning is not a kind of a thing English SE is supposed to specialize in, but before looking for possible figurative meanings of the song excerpt that I put below I just want to reassure the phrase in bold is not a rare idiom or something.
There is a song by Pink Floyd – Arnold Layne. It has the following lines:
Oh, Arnold Layne
It's not the same, takes two to know
Two to know, two to know
Why can't you see?
What does (it) takes two to know mean? Is it an idiom?
My first thought was that the construction "so far as concerns X" was simply ungrammatical, and that it should be "so far as X is concerned". But as this chart shows, it's just fallen out of favour...
It's hard to find single-word X's that occur often enough to track usage change over time, but the 43 actual instances of "so far as concerns spirit" seem to be mostly C19, whereas 44 instances of "so far as spirit is concerned" are mostly C20. But there's no difference in meaning involved.
As far as Pink Floyd coining it: "no." I found a reference to a book published 1970 which uses the phrase in the same manner ( "19 Necromancers from Now", Doubleday 1970, Ishmael Reed link ). "Shine On" was released c. 1975.
For the date range 1/1/1800-12/31/1979, this was the only reference to the phrase (in "google books") which was not of the sort "... steel. Breeze ..." etc.
Best Answer
Yes it is an idiomatic expression:
It takes two :
(Collins Dictionary)