Sophie Germain made important contributions to number theory and theory of elasticity. But how did she learn mathematics, if in those days women were not allowed in the universities nor they were members of the scholar's societies? In Sophie’s Diary the author gives a perspective of how, being an adolescent, Germain may have learned mathematics, reading the books written by the ancient mathematicians and other great scholars of her time.

Sophie’s Diary contains a glimpse of Parisian life during the French Revolution in the years between 1789 and 1793. The book also includes fragments of the history of mathematics and the topics that Germain must have learnt to develop her famous theorem.