| Quote #1
And this same flower that smiles to-day
There's something strange about the certainty with which the speaker describes the death of the flower. He doesn't say it "might die tomorrow" or "it could die," but rather it "will be dying." It's as if he wants to drive home the certainty of death. The lines enact the suddenness and surprise that death can occasion by juxtaposing "to-day" and "to-morrow" so closely (the former ends one line while the latter begins the following one).
| Quote #2
The sooner will his race be run,
The speaker is talking about the sun, but we know he's really talking about death. Or is he? The speaker wants to emphasize the fact that we're always one step closer to death, but everybody knows the sun will rise again in the morning. Whether he wants to or not, the speaker ends up suggesting that, perhaps, there are second chances. Yeah, sure, maybe the virgins will get older, but perhaps they can metaphorically "rise" again.
| Quote #3
But being spent, the worse, and worst
These lines imply that the progression from youth to age is something of a miniature death. This is evident here in the use of the word "spent," which means something like "used up," "gone," "no more." It's also evident in the progression from "worse" to "worst."