Gather ye rose-buds while ye may.
Old time is still a-flying:
And this same flower that smiles to-day
To-morrow will be dying.
The rose-buds are a metaphor for the inherent sexual ripening of virgins.  The  carpe diem  theme is clear.  The speaker is urging the young women to ‘seize the day’, to value what they have in terms of sexual attractiveness and enjoy it while they can. 
