[Hamlet:] . . . who would fardels bear,

To grunt and sweat under a weary life,

But that the dread of something after death,

The undiscover’d country from whose bourn

No traveller returns, puzzles the will

–Hamlet,
William Shakespeare

What does Hamlet mean when he refers to the "undiscover’d country"?

the afterlife
Denmark
foreign lands
his own mind