"Old Time Is Still A-Flying"

Dominic Flandry analyzes the current military and political crisis, then says:

"'...never mind, sweetheart! Let's enjoy ourselves while we may.'"
-Poul Anderson, The Game Of Empire IN Anderson, Flandry's Legacy (Riverdale, NY, 2012), pp. 189-453 AT CHAPTER TWELVE, p. 325.

He speaks in a grand literary tradition:

"Gather ye rosebuds while ye may,
"Old Time is still a-flying:
"And this same flower that smiles to-day
"To-morrow will be dying."
-see here.

"Oh, come with old Khayyam, and leave the Wise
"To talk: one thing is certain, that Life flies;
"One thing is certain, and the Rest is Lies;
"The Flower that once has blown for ever dies."
-see here.

And how often does Shakespeare evoke the passage of time?