I fear, too early, for my mind misgives
Some consequence yet hanging in the stars
Shall bitterly begin his fearful date
With this night's revels, and expire the term
Of a despisèd life closed in my breast
By some vile forfeit of untimely death.
In this first quotation, Romeo alludes to the stars, which many people in Elizabethan England believed were responsible for determining one's fate, and speaks metaphorically about a fearful "consequence" which he imagines is hanging there. The verb "hanging" suggests that this will fall upon Romeo's head soon enough. He also personifies fate here, and he is anxious that he (fate) will "begin his fearful date / With this night's revels." The personification of fate presents the idea that fate is a character stalking Romeo throughout the play, waiting to enact the aforementioned fearful consequence.
O, I am fortune's fool!
Here, Romeo again personifies fate and complains that he is being made a fool of by fate. The allusion is to a king and his jester. The king would amuse himself with the clowning of the jester and get rid of him once he was bored. Romeo is afraid that fate will do likewise with him.
O God, I have an ill-divining soul!
Methinks I see thee, now thou art below,
As one dead in the bottom of a tomb.
Either my eyesight fails or thou look'st pale.
In this quotation, Juliet imagines, as Romeo climbs down from her balcony, that she sees him "dead in the bottom of a tomb." The tomb here, of course, symbolizes death and foreshadows that Romeo is heading toward his death.
Will I set up my everlasting rest
And shake the yoke of inauspicious stars
From this world-wearied flesh!
In this fourth quotation, Romeo decides to lay himself next to Juliet and die alongside her. In so doing, he says he will "shake the yoke of inauspicious stars," which, translated, means that he will finally be able, in death, to free himself from the fate (symbolized by the stars) which has been stalking him throughout the play. A yoke is a wooden crosspiece used to attach an animal to a cart. So, in this metaphor Romeo is the animal, and the cart, which determines where the animal goes, is fate.