I always thought that was a strange expression. The world is my oyster.
I imagine the saying as a truncated version of a longer thought. The world is my oyster, and I’m a tiny piece of dirt being digested into a pearl.
And, while, indeed, the saying as popularized is not complete, the original meaning is quite different from the one I inferred.
Why, then the world’s mine oyster,
Which I with sword will open.
Pistol tells Falstaff in the Merry Wives of Windsor. Falstaff had just declined the noble Pistol a loan.
The world is my oyster may indeed mean that anything is possible. But that valuable pearl doesn’t come effortlessly. It takes strength, effort, violence perhaps, to pry open and retrieve.
The world is my oyster, Pistol is saying, and I will do whatever it takes to get the pearl.