Kitzot Hachoshen: Blessings of the Torah
The 19th of Tevet is the Yahrtzeit of Rav Aryeh Leib HaCohen Heller, author of Ketzos Hachoshen, Avnei Miluim, and Shev Shmaatsa (1813) The Ran asks that since we know that each Mitzvah has the ability to give us eternal life, and each sin has the ability to cause eternal death, how is it that we can rely on Halachic decisions, even when we know the human beings err? If a doctor declares a poison to be good for you, will that prevent it from killing you? Just because someone is told that a specific action is good, how can that instruction protect him if the Rabbi made a mistake?
The power of fulfilling the commandment to obey the Sages has the ability to give us eternal life even if a mistake was made!
This is the meaning of, “He planted eternal life in our midst,” which means that God gave us the commandment to obey the Sages, and that Mitzvah guarantees our eternal life when we obey.