To know from nothing

[JPablo]

I am not totally sure if "to know from nothing" is an idiom and/or should be taken literally.

My context is regarding a public individual who was supposed to be "sane", yet, in personal contact, happened to be totally "crazy".

Here are a couple of sentences,
The guy’s stark staring mad. He couldn’t talk, he couldn’t answer questions, he was over the hills and far away and actually in direct contact, he knew from nothing.

The question is whether this is simply "no sabía de nada" or has any other meaning.

Thank you in advance for your input!

[Perikles]

I've never heard the expression, and BNC only gives one reference.

[poli]

I suspect this phrase comes from Eastern European immigrants..(Yiddish German, Polish). I think a Spanish translation would be no sabe ni....
Right now I cannot think of the noun to complete the phrase, but if there is one, please let me know. Thanks

PS is the noun narices?

[JPablo]

Oh, thank you Perikles & Poli...
I just found this, (with the addition of "not") (This kind of makes sense in the context... what do you think?)

not know from nothing Inf. to be stupid, innocent, and naive. (This nothing is not replaced with something. Usually used with don't, as in the examples.) Old John—he don't know from nothing. What do you expect from somebody who don't know from nothing?

@Poli, I think in Spanish you can say "no sabe ni narices" "no sabe ni papa..." "no sabe na" "no se entera" "está en Babia" "en las Quimbambas" algo de ese estilo creo que me vale en el contexto...

[poli]

to know from nothing sounds a little bit better than not to know from nothing. The fact that Perikles has never heard the term gives support
to my idea that this phrase has an Ellis island sound to me. Many of these immigrant expressions from Eastern and Central Europe have
found their way to Britain from movies and acquaintances, but not this one apparently.

Example: When the interrogators want to find out if the bank robbers
girlfriend is in on the heist, the thief may say I tell you she knows from nothing. A less well educated thief may say I tell ya, she don't know from nuttin'

[JPablo]

Gotcha!
That kind of makes sense. Thanks. Sounds like a very good example.

[CrOtALiTo]

Originally Posted by JPablo

I am not totally sure if "to know from nothing" is an idiom and/or should be taken literally.

My context is regarding a public individual who was supposed to be "sane", yet, in personal contact, happened to be totally "crazy".

Here are a couple of sentences,
The guy’s stark staring mad. He couldn’t talk, he couldn’t answer questions, he was over the hills and far away and actually in direct contact, he knew from nothing.

The question is whether this is simply "no sabía de nada" or has any other meaning.

Thank you in advance for your input!

It'a simple phrase right?