What is the significance of Laura's glass menagerie, especially the symbolic unicorn, in Tennessee Williams' play The Glass Menagerie?

In addition
to the glass menagerie, especially the glass unicorn, symbolizing Laura's fragility and feelings
of freakishness, the glass further symbolizes her hidden inner
radiance. Her inner radiance is symbolized through the glass's ability to radiate
light, as she points out to Jim when she hands him the unicorn: "Hold him over the light,
he loves the light! You see how the light shines through him?" (Scene VII). Little does she
realize that she equally emits light due to her gentleness,
goodness, and prettiness. The loss of the unicorn's horn further symbolizes Laura
shedding her belief that she is "freakish," a belief Jim
helps her shed by commenting that he never noticed her brace and that he wished she had made
more friends, and by conversing with her, dancing with her, calling her pretty, and kissing
her.

Yet, one may argue against the interpretation that Laura giving him the
broken unicorn after he announces he is engaged means that she is relinquishing her
understanding...