This extract is taken from the novel The House on the Old Road by Isabel Vargas.

The House on the Old Road (extract)

The piano had not been tuned in forty years. Benedita knew this because her aunt had told her on the day she arrived, standing in the doorway of the sitting room as if presenting evidence. It had belonged to her grandmother, the aunt said, who had been the last person to play it, and after her grandmother died the house had sort of locked itself around the
5 piano, the way a tree grows around a nail.

It was an upright piano in dark rosewood, with two keys that did not work and a pedal that stuck. Benedita lifted the lid sometimes in the evenings when she was alone and pressed the keys one at a time,
listening to what was there. The notes that worked sounded perfectly ordinary. The two silent keys seemed, to her, louder than the rest.
10

She had not played piano since she was twelve. That was fifteen years ago, in another city, in another version of herself that she had been careful to leave behind. She did not think of herself as a person who played piano. She was not certain, now, what she had left behind along with it. 15

There were photographs on top of the piano: her grandmother at twenty, at forty, at sixty; the same face becoming more deliberate with age, as if certainty were something that accumulated. The grandmother
in the last photograph was looking slightly past the camera. Benedita looked at the same point now, and saw the door.

Benedita pressed the silent key again.
20 She did not know what she was asking.

How and to what effect is symbolism used in this text?