how does the poem mirror the narrators sense of ushers mental instability

The first four verses can be interpreted to describe the Usher household and family mansion the way it once might have been. It is green, with seraphs, yellow banners, and a sense of well-being all around the area. In verses five and six, however, the mansion is taken over by "evil things in robes of sorrow" that change the beauty from good to bad.

"A hideous throng rush out forever, And laugh—but smile no more." This is the state of the mansion in the poem, once happy but now throwing out the residents in a rush. There are no more smiles.