Parashat Ki Tissa – Who is Responsible?

The sin of the golden calf is undoubtedly one of the most famous stories in the Torah. While Moses ascended Mount Sinai, he ensured that there would be spiritual leadership in his absence to guide the people and lead them. How can one explain that Aaron, Hur, and the elders didn’t prevent the sin of the golden calf? How is it possible that Aaron took part in this event?