The mirror that the Lady of Shallot uses to view what is outside of the tower represents how people can view things with an altered sense of reality. The lady could only view the outside world through her mirror, which did not satisfy her and which altered her view of the outside world. Despite knowing that she would die if she viewed what was outside the tower with her own eyes, she decided that she would rather see it for herself and see its beauty, so she climbed down from the tower and floated off in a boat down the river, dying along the way.
There are indeed many symbols in the Lady of Shalott. The first image that comes to mind is that of the ivory tower motif, which is used to signify the lady's pedestal above the ordinary. She remains isolated from the commo materialistic world and is rather part of a higher artistic realm. WE must also remember that the mirror signifies an idea prevalent at the time that artist creates representations of reality. The curse is also a significant as it depicts the stereotype that the artist and the common man cannot mingle.