Beginning: The poem begins with a sense of melancholy and resignation. The speaker laments the passing of time and the inevitable approach of death, comparing himself to a summer day that is slowly fading away. The mood is one of sadness and acceptance of mortality.
End: In contrast to the somber tone at the beginning, the end of the poem takes on a more positive and hopeful note. The speaker finds comfort in the idea that his love for the person addressed in the poem will survive beyond death and live on even when his physical body has perished. This shift in mood suggests a sense of transcendence and the power of love to overcome the boundaries of mortality.