This poem describes Xu Hun entering Yaotai in the early morning and feeling a fresh and mysterious atmosphere. He saw dozens of people at the banquet, drinking and having fun, and a beautiful woman invited him to write poems together. However, when he was about to write a poem, his dream woke up. He only remembers the last sentence of the poem: "The dust is not exhausted, and the moon is bright at the foot of the mountain."
The "unfinished heart" in this poem means that the worldly troubles and distractions still exist in Xu Hun's heart, but he is not completely detached. And "ten miles below the mountain, the moon is bright" means that he experienced the washing and sublimation of his heart in the early morning and felt the emptiness and clarity of his heart.
Therefore, this poem can be understood as: even if the troubles and distractions in the world still exist, as long as we can calm down and think seriously, we can find a clear and ethereal feeling in our hearts.