_"To be, or not to be: that is the question:
Whether 'tis nobler in the mind to suffer
The slings and arrows of outrageous fortune,
Or to take arms against a sea of troubles,
And by opposing end them. To die: to sleep;
No more; and by a sleep to say we end
The heart-ache, and the thousand natural shocks
That flesh is heir to, 'tis a consummation
Devoutly to be wish'd. To die, to sleep;
To sleep, perchance to dream: ay, there's the rub;
For in that sleep of death what dreams may come,
When we have shuffled off this mortal coil,
Must give us pause: there's the respect
That makes calamity of so long life;
For who would bear the whips and scorns of time,
The oppressor's wrong, the proud man's contumely,
The pangs of despis'd love, the law's delay,
The insolence of office, and the spurns
That patient merit of the unworthy takes,
When he himself might his quietus make
With a bare bodkin? 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,
And makes us rather bear those ills we have
Than fly to others that we know not of?
Thus conscience does make cowards of us all;
And thus the native hue of resolution
Is sicklied o'er with the pale cast of thought,
And enterprise of great pitch and moment
With this regard their currents turn awry,
And lose the name of action."_
In this passage, Hamlet is grappling with the existential question of whether it is better to live or to die. He weighs the pros and cons of life against the uncertainty of death. One of the main reasons why he hesitates to commit suicide is the fear of what might happen to him after death. He wonders what kind of dreams he might have and whether they will be pleasant or terrifying. This uncertainty, or "rub," gives him pause and makes him reconsider his plan.
The phrase "there's the rub" has come to be used more generally to refer to a difficulty or obstacle that prevents something from being achieved or accomplished. It is often used in a humorous way to acknowledge a minor inconvenience or annoyance.