In the Time of the Butterflies jumps between the present (a.k.a. 1994) and the past, which spans from 1938 to its main characters' deaths in 1960. Only one character—the surviving sister Dedé —is the link between now and then. She's the only one who carries the torch of memory.
Memory is not exactly trustworthy in the novel, and this reminds us that it is a novel, a fictional invention that happens to star historical characters. But the past that this novel portrays is real enough, with historical dates and facts filling in the context.
Questions About Memory and the Past
What does Dedé mean when she says that the girls' spirits have been with her all afternoon?
Who taught Dedé her trick of remembering a happy memory?
Why does Dedé disapprove of Fela's channeling the girls?
Chew on This
Dedé is the fulcrum that the past and the present balance on.
The author reminds us that memory is fallible so that we will accept the fictional inventions she creates.