"The war tried to kill us in the spring" from The Yellow Birds always stuck with me, for its complete decoupling of the war from the men who had come thousands of miles to fight it.

** ETA the full opening:

“The war tried to kill us in the spring. As grass greened the plains of Nineveh and the weather warmed, we patrolled the low-slung hills beyond the cities and towns. We moved over them and through the tall grass on faith, kneading paths into the windswept growth like pioneers. While we slept, the war rubbed its thousand ribs against the ground in prayer.

"The moon blew up without warning and for no apparent reason." - Seveneves

"All this happened, more or less." - Slaughterhouse-Five

There’s also: “It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife.”

Curiously, it seems difficult to find John Donne's Meditations XVII with the original language. The spelling has been modernized everywhere I can find it online.

(I suppose this technically isn't the opening line, but it's the first line used when most people quote the passage.)

No man is an Iland, intire of it selfe; every man is a peece of the Continent, a part of the maine

“The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents.”

Though for me it’s the second line that nails it: “We live on a placid island of ignorance in the midst of black seas of infinity, and it was not meant that we should voyage far.”

From memory: The sky was the color of a TV tuned to a bad channel

last night i dreamt i went to Manderley again

"All happy families are alike; each unhappy family is unhappy in its own way" -- Leo Tolstoy, "Anna Karenina"

"Into the face of the young man who sat on the terrace of the Hotel Magnifique at Cannes there had crept a look of furtive shame, the shifty hangdog look which announces that an Englishman is about to speak French."

― P.G. Wodehouse, The Luck of the Bodkins

Being English, from the south, where learning French to only a poor standard is a common pastime, you can just picture it instantly.