Meaning of the word "beware of a man of one book" in English

What does "beware of a man of one book" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

beware of a man of one book

US /bɪˈwer ʌv ə mæn ʌv wʌn bʊk/
UK /bɪˈweər ɒv ə mæn ɒv wʌn bʊk/
"beware of a man of one book" picture

Idiom

a warning that a person who has mastered one single subject or perspective can be a dangerous or formidable opponent

Example:
He has studied that legal code for thirty years; beware of a man of one book.
In a debate, beware of a man of one book, for his knowledge of that topic is exhaustive.