In "Spring and Fall," how does the mood of the poem change from the beginning to the end of the poem?

In the beginning of the poem, the mood is reflective and melancholic as the speaker addresses a young girl named Margaret and tries to explain to her the concept of aging and mortality. The speaker speaks empathetically to Margaret, acknowledging her sadness and sensitivity towards the changing seasons and the falling leaves.

However, as the poem progresses, the mood becomes more resigned and accepting of the inevitability of change and loss. The speaker consoles Margaret by telling her that it is natural to grieve for what is lost and that she will grow to accept these feelings as she gets older. The poem ends on a note of acceptance and understanding, as the speaker reassures Margaret that despite the sadness of fall and mortality, there is beauty and renewal in the cycle of life.