How, among all the laws reportedly given on Mount Sinai, did the Ten Commandments become definitive for the Israelites and later, the Christians? There are several variations of the Decalogue in the Old Testament, so why were these different versions created? Here Harvard professor Michael Coogan discusses the meanings that the Ten Commandments had for audiences in biblical times and traces how their context has changed over the past three millennia, while offering a pragmatic view of how this foundational text may best be understood today.