Why do you think Minerva was nicknamed the butterfly and when her sisters joined the movement they were known as Las Mariposas?
Julia Alvarez's In the Time of Butterflies is an emotional history, rather than one of fact, involving the despotic reign of Rafael Leónidas Trujillo, dictator of the Dominican Republic and the brave young women who fought against him. The first of the sisters to understand that Trujillo's reign is one of patriarchal tyranny, Minerva rebels against the patriarchal control of her own father, who orders her to not see a young revolutionary doctor named Virgilio "Lio" and hides his letters from her. She later recognizes this same male domination in Trujillo and resists it as well.
In her growing maturity and resistance, Minera is nicknamed la mariposa, the butterfly. Secretly, she listens to the radio and becomes active in the resistance; this radical change in Minerva is the reason for her name; for, she has been cloistered in her life and only now emerges from the chrysalis of her home. Clandestinely, Minerva listens to underground radio and joins the movement against Trujillo. Later, Minerva declares,
"Adversity was like a key in a lock for me. As I began to work to get our men out of prison, it was the old Minerva I set free." (Part III, Ch 12)