I am trying to find an equivalent of a Russian saying which means that it is simply/humanly impossible to do something. I have read the answers from the post Phrase for saying something is impossible at all and What is the equivalent of Persian idiom "When the reed blooms"?, but what I would need is a structure similar to:

You can't have the cake and eat it.

This saying focuses on the fact that you can do only one thing at a time, that you can't have both options. But what I need is something that underlines the sheer impossibility to do something.

I tried to Google You can't *, but nothing comes up that makes sense in my context. Are there any idiomatic expressions beginning with You can't ____? The expression can be unilateral (unlike the example with the cake). I can make up something just to make it clearer:

  • You can't freeze hell.
  • You can't drink the sea.
  • You can't see with the back of your head.

PS: If the phrase can be something you cannot do with a member or part of your body (as in the third example I made up), it would be even better. But if there is nothing of the sort, I will accept anything with this meaning.

  • You can't make a silk purse out of a sow's ear springs to mind, but this refers specifically to the impossibility of making something good out of poor materials. Commented Nov 2, 2022 at 17:20
  • Like Kate Bunting, I can think of other more specific idioms (e.g. you can't squeeze blood from a stone). If you don't find a good all-purpose idiom, maybe some of these specific ones will suffice.
    – Juhasz
    Commented Nov 2, 2022 at 17:25
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    Japanese language has a great idiom for the impossibility of doing something: 網の目に風とまらず "You can't catch wind in a net". I would adopt it.
    – ermanen
    Commented Nov 2, 2022 at 17:35
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    @ermanen That is very similar to the English expression about carrying water in a sieve. Commented Nov 2, 2022 at 18:16
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    @MarcInManhattan Great, along with your answer, I will consider your comment as another option. I am grateful indeed.
    – fev
    Commented Nov 2, 2022 at 18:43

3 Answers 3


The phrase "square the circle" may work for you. From the Collins Dictionary:

to attempt the impossible (in reference to the insoluble problem of constructing a square having exactly the same area as a given circle)

From the Cambridge Dictionary:

If you try to square the circle, you try to do something that is very difficult or impossible.

In your sentence, I'd probably change "the" to "a":

You can't square a circle.

  • Dammit! You beat me to it.
    – user405662
    Commented Nov 2, 2022 at 18:14
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    @MarcInManhattan That must be it! Just right for what I need.
    – fev
    Commented Nov 2, 2022 at 18:36

I'm not sure— since what's given isn't contextualized at all— if the idiom I offer would blend well with what it's a part of (which I presume to be some sort of writing), but it is certainly along the lines of those already supplied by the OP and others. To the mathematically minded, this might appeal at once(if they didn't know such an idiom was there in the first place.)

You can't square the circle


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    If two minds of respectable users think of the same, that must be it!
    – fev
    Commented Nov 2, 2022 at 18:37

What is done cannot be undone.

A mill cannot grind with water that is past

A zebra can't change its stripes

There are many other examples at "Free idioms dictionary by FARLEX(https://idioms.thefreedictionary.com/cannot)"

Actually I was trying to remember two particular idioms, one had the meaning of "words are like arrows shot, not quiverable" or something like that, the other was a particular example of an idiom with this phrase "the same odds as.....". They are eluding me at the moment. I will update my answer if I remember them.

  • +1 for the zebra. If there were something similar about man, it would be great. I will keep searching for a while, but I can't complained, I have received such good suggestions already!
    – fev
    Commented Nov 2, 2022 at 18:45

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