Everything in "Fall" turns on a single word with two meanings. The speaker begins by poking at it: it's the season, but it's also tumbling, slipping, stumbling. That playfulness fades quickly into something more wistful. Autumn brings rain, melancholy, and old bittersweet memories that return to unsettle a restless mind. Winter, the speaker half-jokes, might actually be easier, since it won't feel so insecure.
Then the mood lifts. The third stanza turns toward new friends, new experiences, and new lives, and offers a small comfort: it's never fully dark, even once the summer heat is gone. The final stanza hands the choice to the reader. Fall can be bright or very dark, and what matters is how you meet it. Will you fall, or will you rise?
The tone is thoughtful and gently hopeful, with a little uncertainty underneath. The repeated one-word line "Fall" works like a pause for breath before each new thought.