There's no 'mystery' (to/as to/about) why we're here. = It's no 'mystery' why we're here. [=we know why we are here]
His success is something of a 'mystery'. = His success is a bit of a 'mystery'.
We'll reveal the identity of today's 'mystery' guest after these commercials.
(..) - There is no softer ground than town. - That almost rhymes. He's our poet laureate. Come on. I agreed to spend the afternoon, if only to understand... ...the mystery of how a place could feel so strange and yet so familiar. I've been working on this poem for years. Really? (..)2003 Big Fish