Sophie Germain was a real-life 18th century French mathematician, and Catherine looks up to her for her genius and for her persistence in the face of rampant sexism. In fact, Catherine first brings up Sophie Germaine in a moment when she herself is facing sexist assumptions about women in math. Hal has just implied that all mathematicians are men, so Catherine relays the story of Sophie Germain teaching herself advanced math while trapped in her home during the French Revolution. Germain wanted to study at a university, but none would accept women, so she furthered her career another way: under a male pseudonym, she wrote to a famous mathematician (a man named Gauss), and he mentored her via correspondence. In this way, Germain was able to produce groundbreaking mathematical work—and, once she was recognized for her abilities, she was able to reveal her true identity to Gauss, who remained supportive. While Germain lived centuries before Catherine, the two women share a struggle with sexism in math. Like Germain, Catherine has uncanny mathematical abilities that she struggles to convince others to recognize, and like Germain, Catherine has to produce groundbreaking work in order to be seen as credible at all.