The speaker starts out almost laughing at their own failure. Beauty is falling everywhere, so fast and so thick that there's no way to take it all in. Rather than keep trying, they give up, sit down, and let it rain. The repeated lines, "beauty raining down on me" and "all over me," make the moment feel overwhelming, but not unpleasant.
In the middle stanza, the poem shifts to "you" and imagines a relationship between a person and beauty. Beauty is the host, and we are only guests. Guests are supposed to be humble, and the speaker says you "pale" in front of beauty, as if you can't match it.
The ending turns that humility into something freeing. Perfection isn't something to chase or earn; you let it flow over you. The final instruction is almost startlingly simple: just say, "Thank you." The mood is calm, grateful, and a little playful, a reminder that sometimes the best response to something wonderful is to stop struggling and receive it.