I have a question related to the meaning and possible obsoleteness of the expression "a host in oneself". As my dictionary says, this expression can be applied to a person who is a brilliant worker and do as much work (whether quantitatively or effectively) as other ten workers would do. (In my language it'd be "one worker costs ten others").

The question is can you associate the above-mentioned expression with the provided meaning? And if so, is this expression generally used or is it archaic?

I already had a conversation with Mr Wordy on this theme, and he presumed that this expression was in use formerly but now it's obsolete.

Could you provide your opinion?

Thanks in advance.

I've never even heard the phrase before. I'd say 100% obsolete.
It saddens me that something written during the lifetimes of those now living is obsolete, but I remind myself that our purpose is to teach modern casual English.
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victor_amelkinThe question is can you associate the above-mentioned expression with the provided meaning?
I might not understand you correctly, but provided is generally conjuction meaning "on the condition or understanding that".

It's an idiomatic expression. There are some examples my Lingvo gives me:

I... work as ever, and just tower above our troubles. Mamie is a host in herself. (R. L. Stevenson and L. Osbourne, ‘The Wrecker’, ch. XVI)

Princess: "...You must go and dance." Fleming: "...There are enough men without me. I'm sure Thornton Clay is a host in himself." (W. S. Maugham, ‘Our Betters’, act II)

Obsoletness is a question of style, I suppose. You can use it if you gasp for it. However, I'd like to go along with that Mr.Wordy told you.
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Hi folks,

Thanks for your answers. Apparently, it'd be better not to use this expression
since nobody understands its meaning.

Fandorin> Obsoletness is a question of style, I suppose.

I'll be so bold to disagree with you. It's rather a question of whether an addressee
of the message will understand it. In most cases it makes no sense to use expressions
reader won't understand even if the usage of such unintelligible expressions inheres
to your writing style. But anyway, thanks for sharing your opinion, it's highly appreciated.