Time is full of sunrises and sunsets.
Two complete opposites, yet one cannot exist without the other. The sun cannot rise in all it's glorious brilliance, lest it has set beforehand; while the romantic, rosy delight of a sunset cannot have its splendor without the mellow fantasy of the sun rise.
Even as the earth shattering clash of the cymbals of a symphony may symbolize the beginning of a brilliant masterpiece, and the tame, but elegant utterance of the French horn signifies the divine close; even so, the transition to day and night works in utter discord, yet splendid harmony.