Moshe Rabbeinu reviews the various travels of עם ישראל in the desert. He refers to חטא העגל as ודי זהב, the place of ודאי זהב, when there was enough gold.
The Gemara in ברכות says that Moshe argued with Hashem that it was not the fault of the Jewish people for making the Golden Calf. Had they not been given the Egyptian treasures, they would not have had the means to build it.
Yet, this argument is not mentioned in the Torah. Instead, Moshe asks for forgiveness and accepts guilt. He felt that this set a superior precedent for future generations. It was only a leader like David who accepted guilt for his sin with Bat Sheva. Others, like Shaul, chose to put the blame on others. It takes a big person to accept responsibility for his actions. This is what Moshe was also trying to teach future generations. We are likely to make mistakes in life, but we need to ask Hashem for forgiveness in order to move on.
These nine days are certainly meant for introspection and reflection. We must learn from the past in order to bring the גאולה. May it come speedily.