Friendship
Friendship is one of the most important and significant themes in The Book of Goose. Growing up, and for much of their lives, Fabienne and Agnès were the best of friends. They did everything with each other and would have sacrificed anything in order to keep each other safe and happy. They were each other's support systems in tough times (war) and good times (when Fabienne helped Agnès escape the French countryside they grew up in). Their friendship was what held the two together in bad times and allowed them to survive and remain mentally sane.
War
War is one of the most important themes in The Book of Goose. The novel is presumably set during World War II and after the war, which destroyed much of Europe. War is constant in the lives of Agnès and Fabienne, as well as the rest of the French population. And war caused both Agnès and Fabienne tremendous grief and trauma; it ultimately upended their lives and caused them to seek out different situations in which they could be safe and successful. For the characters in the novel, war and its destructive effects is the single most transformative event in everyone's lives.
Cultural differences
The cultural differences between two countries (France and America) are an important theme in The Book of Goose. After going through terrible and traumatizing experiences together, Agnès and Fabienne find themselves in different cultures. Fabienne remained in France, while Agnès moved to and lived in America for many years. Fabienne remained in a culture that she was deeply familiar with. When Agnès went to America, however, she left a culture she was intimately familiar with (France) and goes to America, where she must quickly learn and acclimate to the country's culture. The culture in America, after all, is very different from the culture in France. This dichotomy reinforces how differently the world lives and how much Agnès relied on Fabienne to live a long and successful life.
