How we cite our quotes: (Act.Scene.Line). Line numbers correspond to the 2008 Norton edition.
Quote #1
Come, temperate nymphs, and help to celebrate
A contract of true love. Be not too late. (4.1.148-149)
As a gift to the young couple, Prospero puts on a masque (a fancy, courtly performance with music and dancing) to celebrate Miranda and Ferdinand's "contract of true love." Interestingly enough, in the winter of 1612-1613, The Tempest (along with thirteen other plays) was performed in honor of the marriage of King James I's daughter Elizabeth to Frederick (the Elector Palatine). Some scholars think that Prospero's "wedding masque" was added by Shakespeare just for this performance but other critics say there's no evidence that it wasn't an original part of the play.
Quote #2
Go bring the rabble,
O'er whom I give thee power, here to this place.
Incite them to quick motion, for I must
Bestow upon the eyes of this young couple
Some vanity of mine art. It is my promise,
And they expect it from me. (4.1.40-45)
Prospero doesn't only practice his art for practicality's sake. Like many artists, he wishes to be admired for his incredible skill.
Quote #3
PROSPERO
I had forgot that foul conspiracy
Of the beast Caliban and his confederates
Against my life. The minute of their plot
Is almost come. (4.1.155-158)
In the middle of the dazzling performance of the wedding masque, Prospero is suddenly reminded of the "foul conspiracy" against his life. This reminds us that the magic of the theater has the capacity to suspend time and make us forget (if only for a short time) the problems of the real world.