The "morals" or "lessons" presented in novels are often drawn directly from key themespresented in the work. In order to define a lesson from any novel, it is easiest to start by looking at a theme (or more than one) and asking yourself after reading, "What message is the author sending about this theme?"
Sarah's Key is a story about the Holocaust. If you have studied the Holocaust, either from a literary or a historical standpoint, you know that one key message we continue to take away from this dark time in history is, "How do we prevent such a thing from ever happening again?"
One key to Hitler's success in mass genocide was the fact that for so long, everything was kept secret. Certainly someone (the United States and others) would have intervened sooner, had we only known the truth of what was really going on, not only in concentration camps, but in the many years that preceded the worst of things. Even the Germans themselves were brainwashed over a period of several years and kept in the dark about what Hitler really planned to do (and was doing).
In the wake of the Holocaust and as a result of the secrecy, the entire world has experienced, in one form or another, a deep sense of guilt.
Two key themes of Sarah's Key are secrecy and guilt. On a narrow scale, it begins when Sarah's own parents are not forthcoming with her about the reality of what is going on when her family is taken from their house. She has locked her brother inside a hidden cabinet assuming she will be able to return to let him out. Sarah lives with the guilt of her brother's death for her entire life.
As other characters in the story are introduced to more of the secrets of the Holocaust (and of history), including Sarah's story, they are also filled with sadness and guilt. Julia expresses this when she says:
Sorry for not knowing. Sorry for being forty-five years old and not knowing. (192)
These small examples of secrets and the resulting guilt are merely a reflection of the bigger picture of the entire Holocaust itself. Individually, you could now draw several conclusions about the moral or lessons that lie within as you apply them to your own experiences. One moral I personally take away from this book (and others like it) is that knowledge is power, and when we cease to explore, experience, and educate ourselves about the world around us, we risk losing opportunities and feeling guilty later. Along the same lines, when others hide information (or keep secrets), we are vulnerable to oppression.