a riddle wrapped up in an enigma

The phrase "a riddle wrapped up in an enigma" is often used to describe someone or something that is exceptionally mysterious, complex, or difficult to understand. It implies that the subject in question is layered or concealed, like a puzzle within a puzzle, making it particularly challenging to unravel or decipher. The phrase is attributed to Winston Churchill, who used it to describe Russia's intentions during World War II. The enigmatic nature of the phrase emphasizes the deep level of mystery and intrigue surrounding the subject.