What is a summary of the poem "lllustration" by John Ashbery?

In "Illustration" by John Ashbery, a novice nun is sitting on the corner of a building "high over the city," while the police try to convince her to come down. Many people gather below to join in the attempt, with one lady promising "to be her friend" and others offering her nylons, "little offerings of fruit and candy," and flowers. The nun does not come down, but "for that the scene should be a ceremony / Was all she wanted." That is, the nun is gratified to have created a spectacle in the street because she wants "monuments."
The nun speaks, saying she knows the people will offer her "every good thing / I do not want," and she asks them to remember "I died accepting them." With this, she removes her robe and jumps from the building.
The second part of the poem serves as a sort of moral or explanation of this story about the nun. "Much that is beautiful," the poet says, "must be discarded" so that we can achieve a "taller impression of ourselves," just as moths will enter a flame because they want to be the flame itself. The speaker seems to equate the nun to this "flame," saying that we might have "soared from earth, watching her glide," but in the end the nun was only an "effigy of indifference, a miracle / Not meant for us." The nun, in refusing the beautiful earthly things that were offered to her, becomes a "miracle," or a better person in the next life.