The poem's themes contrast the material to the spiritual. In the first three stanzas, the speaker describes how the incarnate aspects of the earth all will die. A beautiful day will "die" when night falls. A rose will inevitably die as well—its root, which makes it grow, also assures its demise. Finally, springtime itself, with all its beauties, will die away. All that is left alive in the end, the speaker states in the final stanza, is " a sweet and virtuous soul."
The main theme of the poem is that the material world is ephemeral: it it constantly passing away towards death. Only the spiritual is eternal. This implies that we should concentrate on ensuring that our souls are "sweet and virtuous."
A second theme, emphasized by images of tears, is that it is sad that the beautifies of the material world must die. The consolation we are left with is faith and a belief in the survival of the immortal soul.