The Mekhilta continues its analysis of how the prohibition against eating meat cooked in milk is established in Torah law. The argument proceeds by comparing meat and milk to other forbidden foods — specifically fats and blood — and showing why a direct comparison fails.
Fats (chelev) and blood are among the most severely prohibited substances in the Torah's dietary code. A person who deliberately consumes forbidden fats or blood is liable to kareth — spiritual excision, one of the gravest penalties in Jewish law. Kareth means being "cut off" from the people of Israel, a punishment understood as divine rather than judicial, affecting the soul itself.
Now, one might attempt to derive the prohibition of meat and milk from the existing prohibition of fats and blood. If fats and blood may not be eaten, and they carry the penalty of kareth, then surely meat cooked in milk — another food the Torah forbids — should also be prohibited. The analogy seems natural.
But the Mekhilta dismantles this reasoning. Meat cooked in milk, unlike fats and blood, does not carry the penalty of kareth. The severity levels are fundamentally different. Since the cases are not truly parallel, you cannot use one to establish the other. A prohibition carrying kareth cannot serve as the basis for deriving a prohibition that does not carry kareth.
Therefore, an explicit verse is required. The Torah must state directly, as it does in (Deuteronomy 12:24) — "You shall not eat it" — to include meat and milk among forbidden foods. Logic alone cannot bridge the gap between prohibitions of different severity. The Torah's own words must do the work.