expression
there is a fine line between genius and insanity
Proverb meaning that extraordinary intelligence and foolishness are surprisingly close; often used to comment on eccentric or unconventional behavior.
彼の奇抜なアイデアを見ると、馬鹿と天才は紙一重だと思う。
Looking at his outlandish ideas, I think there's a fine line between genius and insanity.
Means 'a fine line' or 'a narrow margin'; used in various expressions, not limited to genius and insanity.
A Japanese proverb combining 馬鹿 (fool) and 天才 (genius) with 紙一重 (a single sheet of paper), metaphorically expressing how close the two extremes can be.