These words of Father Restrepo were etched in the family memory with all the gravity of a diagnosis, and in the years to come they had more than one occasion to recall them. The only one who never thought of them again was Clara herself, who simply wrote them in her diary and forgot them. (1.11)
The narrator has referred to Clara's notebooks (which seem to function as a sort of external hard drive for Clara's brain – she writes things down and then forgets them) as a source of information, but the family's collective memory also informs the narrative.
Had it not been for the letters Clara and Blanca exchanged, that entire period would have remained submerged in a jumble of faded, timeworn memories. Their abundant correspondence salvaged events from the mists of improbable facts. (8.1)
The narrator constantly emphasizes writing as a means of solidifying memory – human brains alone are faulty. Journals, letters, and other records provide lasting evidence that events actually happened.
She had decided to forget the man she had married and act as if he had never existed...Clara, who had spent nine years without speaking, knew the advantages of silence and asked her daughter nothing, joining in her efforts to erase all memory of Jean de Satigny. (9.8)
Speech is another way the characters hold on to memory in the novel – by repeating stories, the memories remain real, and may even take on new shades of significance. So not repeating stories is a way of willfully erasing the event from memory.
At the end of his life, when his ninety years had turned him into a twisted, fragile tree, Esteban Trueba would recall those moments with his granddaughter as the happiest of his whole existence. (9.27)
Memory does a lot of things in the novel, such as help the narrator see connections between family members and understand present events. But perhaps one of its simplest and most satisfying functions is to provide a measure of happiness to Esteban Trueba in his old age.
When Alba asked to hear these bizarre stories again, Blanca could not repeat them, for she had forgotten them. This led the little girl to write the stories down. (10.30)
Alba takes up her Grandmother Clara's practice of writing down things she wants to remember – another connection the two women share.
She recalled the past as a series of violent acts, abandonment, and sorrows, and she was not certain things had been the way she remembered. The episode of the mummies, the photographs, and the hairless Indian in Louis XV shoes that had prompted her flight from her husband's house had grown hazy with time. She had told and retold the story of the count's death of fever in the desert so often that she had come to believe it. (10.59)
Silence, for Blanca, helps erase the memory of unpleasant events in her past. Likewise, the repetition of stories that are pure fiction only serves to solidify them until even the storyteller begins to confuse these tales with the facts.
He remembered her as she had been in her youth, when she had dazzled him with the flutter of her hair, the rattle of her trinkets, her bell-like laughter, and her eagerness to embrace outlandish ideas and pursue her dreams. He cursed himself for having let her go and for all the time they both had lost. (11.92)
Jaime's memory, after twenty years of separation from Amanda, no longer corresponds to reality. When he's forced to confront a timeworn, sickly version of the woman he once loved, he has to revise the memory of her as a young, carefree girl who he'd cherished.
I write, she wrote, that memory is fragile and the space of a single life is brief, passing so quickly that we never get a chance to see the relationship between events; we cannot gauge the consequences of our acts, and we believe in the fiction of past, present, and future, but it may also be true that everything happens simultaneously – as the three Mora sisters said, who could see the spirits of all eras mingled in space. (Epilogue.45)
If memory is fragile – it can fade or be manipulated – and the life of an individual is too short to provide much historical perspective, then writing (and reading!) become necessary in order for anyone to be able to understand life.
Here, on my grandmother's table, is the stack of photographs […] everyone, in short, except the noble Jean de Satigny, of whom no scientific trace remains and whose very existence I have begun to doubt. (Epilogue.43)
The lack of documentation of Jean de Satigny's involvement in the family history makes it harder for Alba to believe in him. Here, as elsewhere, we're reminded of the importance of tangible evidence to lend credence to memory.
Clara wrote them so they would help me now to reclaim the past and overcome terrors of my own. (Epilogue.46)
The whole point of remembering the past is, for Alba, to "reclaim" it. She makes it her own (even those events that occurred long before her birth) and uses it to inform her life in the present.