The Torah commands: "You shall not steal." But the Mekhilta asks a question that might surprise anyone who thinks the meaning is obvious — does this commandment prohibit stealing money, or does it prohibit stealing a person? The Hebrew word for stealing covers both property theft and kidnapping, and the distinction matters enormously because the penalties are vastly different.
Perhaps, the Mekhilta suggests, this verse is an exhortation against stealing money — ordinary theft of property. If so, it would be a general financial prohibition, punishable by restitution and fines. But perhaps it is actually a prohibition against stealing a soul — kidnapping a human being, a crime punishable by death.
How do we determine which reading is correct? The Mekhilta directs us to one of the thirteen principles by which the Torah is expounded: a matter is understood from its context. Look at the commandments surrounding "You shall not steal." Immediately before it: "You shall not murder." Immediately after it: "You shall not bear false witness." Both of these neighboring commandments are capital offenses — crimes punishable by death.
If the surrounding laws all deal with capital crimes, then "You shall not steal" must also refer to a capital offense. Stealing money is not a capital crime, but kidnapping is. Therefore, the context determines that this particular "You shall not steal" — the one that appears in the Ten Commandments — is a prohibition against kidnapping, not against property theft.
The prohibition against stealing property exists elsewhere in the Torah. Here, among the gravest commands ever spoken, the stakes are human life itself.