gather ye rosebuds while ye may (to all 18-year-olds I know!)

"To the Virgins, to Make Much of Time" is a poem by Robert Herrick.
The genre of the poem is carpe diem.

Gather ye rosebuds while ye may,
Old Time is still a-flying;
And this same flower that smiles today,
To-morrow will be dying.
The glorious lamp of heaven, the Sun,
The higher he's a-getting;
The sooner will his race be run,
And nearer he's to setting.
That age is best, which is the first,
When youth and blood are warmer;
But being spent, the worse, and worst
Time still succeed the former.
Then be not coy, but use your time,
And while ye may go marry;
For having lost but once your prime,
You may for ever tarry.