As showers from the clouds of summer, (line 27)
This is another cool little man and nature moment. Here he compares summer rain to songs gushing out of the poet's heart (line 26), or to teardrops (line 28). To be fair, people sometimes knock Longfellow for writing lines like this, and we'll admit that comparing tears to summer rain is a little cheesy. Still, we think it's coming from a good place. We also like the way he brings back the rain imagery from lines 6 and 12. Think of it like a little natural echo through the poem.
And the night shall be filled with music (line 41)
Maybe here, in this last line, man and nature come together a little bit. The night, which seemed like such a powerful and strange force in the beginning (remember that eagle?), is now filled with music. If music stands for human art, and night for the power of nature, maybe we're seeing how poetry can tie the spirit and the outside world together. Maybe that goes a little too far, but Longfellow is definitely thinking about how mankind and nature fit together here.