Ki Tavo: The Milestone of Turning Forty
Ki Tavo: The Milestone of Turning Forty

It has become fairly common to hear that “sixty is the new fifty” or “seventy is the new sixty”. While this may appear to be merely a feeble attempt to deny one’s mortality, there is something that affects all of us when we move into a new decade of our lives. The Sages sensed this, and it appears turning forty presents a profound shift in many aspects of a person, most importantly in one’s relationship to Torah.

At the end of the Torah portion of Ki Tavo, Moshe recounts the great wonders God did for the Jewish people during their 40 year journey through the desert. He then says (Devarim 29:3):

But the LORD hath not given you a heart to know, and eyes to see, and ears to hear, unto this day.

The verse is difficult to understand on a literal level. After all, the Jewish people experienced so much during their forty year sojourn; asserting that they did not “know” or “hear” seems preposterous.

The commentators note this problem, and various answers are offered. However, it appears the Sages used this verse as the support for an important idea regarding a person’s age.

In Pirkei Avot (5:24), we find the famous statement of Judah ben Teimah:

He used to say: At five years old a person should study the Scriptures, at ten years for the Mishnah, at thirteen for the commandments, at fifteen for the Talmud, at eighteen for the bridechamber, at twenty for one's life pursuit, at thirty for authority, at forty for discernment (bina), at fifty for counsel, at sixty to be an elder, at seventy for gray hairs, at eighty for special strength (Psalm 90:10), at ninety for decrepitude, and at a hundred a man is as one who has already died and has ceased from the affairs of this world.”

Each one of these milestones requires its own explanation. In this case, the focus will be on turning forty. What does “bina” refer to? Rashi offers two cryptic explanations:

Forty, to understand (lehavin) a thing from a thing and to teach like Halacha. Another version – to understand (levina), as it says there:’ but the LORD hath not given you a heart to know, and eyes to see, and ears to hear, unto this day. From here [we learn] that a student does not understand the knowledge of his rabbi until he is forty’

Of the above two explanations, the first is certainly easier to understand. Forty is the age at which we acquire the means for extrapolation of Torah ideas combined with the ability to render decisions in Jewish Law. This explanation seems to fit the milestone concept of this Mishnah. The second idea, though, is more obscure. The common understanding of Rashi is that the Torah is referencing the Jewish people as students and Moshe as the teacher. If so, how do we understand the verse? What changed after forty years in their relationship to one another? Furthermore, there is a dissonance between the idea of a forty year sojourn, which has nothing to do with age, and turning forty years old, as referred to in the Mishnah.

Before analyzing this specific issue, we should first understand the significance of these ages. Whether the Sages meant the age of forty in a literal way or as more of an idea is difficult to know for sure. However, looking at the entire Mishnah, one can see these ages as notches in a person’s development. If a person is exposed to Torah at a young age, and spends years and years studying the different subjects from his teachers, the concept of forty reflecting a change becomes relevant. The Mishnah is speaking of a progression. The question, then, is what exactly changes with turning forty that drives this progression (this author didn’t feel much different).

Looking at the two interpretations offered by Rashi, one can see a unifying concept, namely the idea of innovation. Rashi first speaks of extrapolation and rendering decisions in Jewish Law. Does this mean prior to forty someone cannot engage in any of these activities? This would be difficult to accept. Rather, Rashi is suggesting that during the first forty years of one’s life, a person is essentially defined by his accumulation of information. Of course he can engage in extrapolation, and if on a high level, is capable of rendering decisions in Jewish Law. He can innovate, but he is not defined as an innovator. At a certain point, forty being the “average”, a person can shift to essentially being defined as an innovator, while still spending his life studying. The scales, so to speak, move to emphasize the ability to innovate.

The second explanation is referring to a different type of innovation. The end of the forty years in the wilderness also meant that the Jewish people were losing Moshe, their rabbi. Throughout their time with Moshe, the entire nation functioned as repositories of the Torah. Moshe taught them, reviewed the concepts and laws, and ensured that they were masters of that which was received at Sinai. At the end of the forty years, the means of becoming progenitors of Torah, rather than only recipients, would be realized. This could be what Rashi is referring to when he speaks of them “understanding” Moshe. They obviously understood the Torah being taught to them. But now they were able to take on the role of perpetuating the Torah to future Jews. 

The Sages felt that this verse was alluding to a shift in their roles. Similarly, the experience of forty years of learning leads to a shift where a person is no longer a student. His ability to comprehend the depths of his rabbi’s insights is the harbinger of becoming someone who gives over Torah to others. The oral tradition of Torah was founded on the principle of ideas and laws being passed down from generation to generation. This Mishnah highlights the stage where a person shifts from receiver to giver.

The difference between these two explanations now becomes easier to understand. Following the sequence outlined in the Mishnah, a person’s relationship to the system of Torah changes dramatically as innovation becomes the norm. In the second idea, the person’s relationship to the tradition of Torah is what shifts, and he becomes defined by the perpetuation of the ideas to the future Jewish people. 

Does this mean turning forty magically produces these results? Of course not. However, if a person dedicates his life to Torah, progressing as set out in the Mishnah, turning forty need not be a rationale for wishing one was younger; instead, it marks the ascension to a new phase in his connection to Torah, in his ability to innovate within the system and to pass on these ideas to the next generation.