Box of chocolates represents results of our choices.
There are numerous choices that we make on daily basis, and then we live with those results.
If you take a piece of chocolate, it looks ordinary from the outside, but only when you break it (make that choice) can you see what's in it: either nothing or a delicious filling.
If you are allergic to something (let's say tree nuts), you will first examine your piece of chocolate, otherwise you can potentially get seriously hurt.
As life goes by (and as you consume more of those chocolate treats), you will find out that you can predict the contents of the choice based on the external appearance (the shape of the chocolate piece, the weight of it, any signs of damage such as filling peeking through if the coating is not even).
This also means that you're becoming more and more full (the novelty of the chocolate is wearing off), and you become more and more discriminating in what you're consuming (this is a relationship to the mortality- you can't do it all, so you do the best you can to make the most of time you have left).
In this respect, it's harder and harder to surprise you (been there, done that) and simple novelty of something is not what you'll jump at (pomegranate filling? gold inclusions? yawn), and you start listening to your inner desires (you take only what you really and truly want, you return to your actual nature), and you don't have to explain anything to anyone.