life is like a box of chocolates
The book Norwegian Wood by Haruki Murakami, first published in Japanese in 1987, and in English in 1989, has the following: "Just remember, life is like a box of chocolates." ... "You know, they've got these chocolate assortments, and you like some but you don't like others? And you eat all the ones you like, and the only ones left are the ones you don't like as much? I always think about that when something painful comes up. "Now I just have to polish these off, and everything'll be OK.' Life is a box of chocolates."
- Life is full of surprises; you never know what will happen next.