All 3 Uses

twilight
in
Go Set a Watchman
(Edited)

...a recurring story as old as time: the chapter which concerned her began two hundred years ago and was played out in a proud society the bloodiest war and harshest peace in modern history could not destroy, returning, to be played out again on private ground in the twilight of a civilization no wars and no peace could save.
p. 122.7 *

twilight = a condition of decline following successes
After dinner she returned to the tree and sat there until twilight, when she heard Atticus call her.
p. 130.9 *

twilight = the time of day between daylight and darkness
Twilights are long, but darkness comes suddenly; the sky turns from dull orange to blue-black before one can take five steps, and with the light goes the last ray of the day's heat, leaving livingroom weather.
p. 133.7

Definitions:

(1) (twilight as in: pink clouds in a twilight sky)
the time of day between daylight and darkness (just after sunset or just before sunrise); or the light from the sky at that time
(2) (twilight as in: the twilight of her career)
a condition of decline following successes
(3) (meaning too rare to warrant focus)
Much more rarely, twilight can refer to