コロンブスの卵たまご

expression, noun

Columbus' egg; egg of Columbus

Refers to a seemingly brilliant idea that appears simple only after it has been demonstrated. Often used when someone belittles an innovation by saying they could have thought of it themselves.

• 彼かれの発はつ明めいはコロンブスの卵たまごだと言いわれた。

  His invention was called a Columbus' egg.

• 成せい功こうしてから「そんなの簡かん単たんだ」と言いうのはコロンブスの卵たまごのようなものだ。

  Saying 'That's easy' after someone succeeds is like the egg of Columbus.