Song speaks of the narrator commanding a rose to go deliver a message of the urgency of his love to his love; "Go, lovely rose!" The rose is a symbol of love and beauty. In this case, in the first stanza, the narrator is telling his girl how beautiful he thinks she is; "When I resemble her to thee, How sweet and fair she seems to be."
In the second stanza, he's asking the rose to tell her that she should not "shun to have her graces spied" as her beauty should not be hidden anymore. He thinks that her beauty should be praised and admired or it will fade without fulfilling its purpose; "where no man abide, Thou must have uncommended died."
In the third stanza, he is telling her that there is no worth in hiding her beauty; "Small is the worth Of beauty from the light retired." He wants her to step out into the light and allow herself to be desired without feeling embarrassed; "Bid her come forth, Suffer herself to be desired, And not blush so to be admired." He wants her to feel proud that she is admired and "not blush."
He ends of with emphasising that at the end of the day, "the common fate of all things rare" is death, which means that beauty fades. The beauty that "they (the rose and the girl) share That are so sweet and wondrous fair!" only lasts for "small a part of time."
This entire poem talk about how beauty fades with time. Thus, like any carpe diem poetry, one is urged to cherish time. In this case, beauty is associated with time and the narrator believes that both should be cherished with the same intensity. There is a tone of urgency to find physical love, as the narrator only addresses physical beauty, which fades. He wants the girl to learn to be "desired" and "admired" while she is still beautiful.
There is a standard structure to the poem, with the first and third line of every stanza being shorter than the rest. This creates a hour glass shape, which could be used to emphasise the subject of this poem - beauty. Also, rhyme is used in this poem. The rhyme is every stanza follows an "a, b, a, b, b" pattern. This rhyme scheme of a repeated "b" creates a drag effect on the poem. I see it as stressing beauty is being sucked (dragged) away with time. Overall, this poem gives me an impression of love being measured in physical appearances.
In the next carpe diem poem, "To the Virgins, to Make Much of Time" the same idea of making full use of time is conveyed. The title itself has already given us a picture of what it is about, with virgins...