Ah, yes, thank you for noticing. It is the opening measure from my favorite part of my favorite opera, Tristan and Isolde, where Tristan implores the night to last forever:
O night of rapture, rest upon us,
Lift our lives remembrance from us.
The second act of this opera is pretty much one long love duet between Tristan and Isolde. Tristan implores the night not to end because he knows that when the sun comes up, he will probably be killed and, well, he is in love with Isolde anyway. When warned by his trusty servant named, hey, there is it: Kurwenal, that the king approaches and Tristan has been betrayed by Sir Melot, Tristan responds: "Let me die here! Let the day to death surrender!"
This being a Wagnerian opera, Tristan and Isolde do eventually die, but not until the next act.
I just realized that there is no coffee in this opera. Well, there should be. Maybe the love potion in the opera is actually coffee.....hmmm.
Yeah, Wagner...that light and frothy stuff.
Couldn't you find anything more serious!?