Among Jews, 120 years is seen as the ideal lifespan. We bless each other to “live to 120” and euphemistically refer to death as “after 120 years.”

Where does this come from, and what does it mean?

The Pre-Flood Ultimatum

The unit of 120 years first appears when reading about the wickedness of Noah’s generation: “The L‑rd said, ‘Let My spirit not quarrel forever concerning man, because he is also flesh, and his days shall be a hundred and twenty years.’”1

The ancient targumim (Aramaic interpretive translations) along with most classical Jewish commentators explain “his days shall be a hundred and twenty years” to mean that G‑d had decided to give the generation of the Flood 120 years to correct their behavior. If they improved their ways, they would be saved; if they didn’t repent before 120 years elapsed, G‑d would cleanse the world with a flood.

Others take this to mean quite simply that humankind’s lifespan is capped at 120 years (indeed, even with the advances of modern medicine, there are still very few documented cases of people living longer than 120).

For more on this see, Can We Live More than 120 Years?

Moses, the Greatest of Men

The number appears again at the other end of the Five Books of Moses, where we read that Moses lived to 120.2 Interestingly, three other great leaders—Hillel, Rabbi Yochanan ben Zakkai, and Rabbi Akiva—also each lived to 120.

Of course, the entire Torah is interconnected, and we can find references to Moses’ longevity embedded in G‑d’s pre-Flood warning. The Hebrew word בשגם, which we translated as “because he is also” has the numeric value of 345, equivalent to numeric value of משה, Moses. The verse can therefore be read, “... Moses is also flesh, and his days shall be a hundred and twenty years.”

This connection was first made by Rabbi Elazar in the Zohar,3 who explains how Moses—the conduit through whom we were given the Torah—is the one through whom we are shielded from death.

Thus, the Zohar continues, it is no coincidence that Moses himself is described as never having passed away. The sun never stops giving light even after it sets. It’s just that after nightfall, the sunlight is reflected through the moon.

In the same way, Moses and his successors in every generation continue to posthumously lead and nourish even after they reach the stage (and age) of 120.

The Rebbe’s Reflection

The Rebbe addressed the significance of this milestone in 1980, as the Chassidic community marked 120 years from the birth of the Fifth Rebbe—Rabbi Sholom DovBer Schneersohn—in the town of Lubavitch on 20 Cheshvan, 5621 (1860).

The Rebbe pointed out that Moses’ continued service is linked to the Torah he transmitted. It follows, the Rebbe concluded, that the way for each of us to tap into the spiritual energy of the Fifth Rebbe is by studying his Torah teachings.

And through the timeless teachings of Torah, we reach a point so deep and so holy that the strictures of time melt away, and we, too, sense the vitality of Moses and his successors in every generation.