R’ Avraham Yafen asks (in haMussar V’ha’Da’as) what kind of shiur this measure of 40 years is. A really bright student might understand his rebbe’s torah faster; a slower student will have to review it more. Someone who is learning every spare minute for years and years will be able to master that much more torah than someone who only learns sporadically. Grasping what a rebbe gives over is a matter of intelligence, diligence, effort – the sheer passage of time, whether one year or 40, seems to have nothing to do with it?
There are two things that a rebbe gives over: 1) knowledge – data, information, facts; 2) behavior – midos, hanhagos, attitude, hashkafa. Of course, says R’ Yafen, a bright student will grasp a shiur far quicker than a slow student and someone who puts in effort will walk away knowing more than a slacker. But Chazal here are not speaking about picking up information from a rebbe, being able to say over a hesber of a Tosfos or a Rambam or having a mehaleich in approaching a sugya. Chazal are speaking about a person’s behavior and conduct, a person’s attitude and outlook on life. That’s not something that can be learned through reviewing a shiur an extra time and is not something that can be acquired with intelligence alone – it’s takes life’s experiences for the message to penetrate and resonate. That’s what takes 40 years to seep in.
Had you told me this answer 20 years ago, I think I would have been skeptical. Now, I think there is a good deal of truth to it. If you ask me about it 20 years from now, I think I will be 100% convinced.
The lesson here is for parents and teachers more than students. Do you have the feeling that you are talking to the walls when you speak to your children? Are they not listening to anything you say? Maybe they are, but you won’t know it until 40 years later. Don’t give up just because you don’t see immediate results, as frustrating as it is (and believe me, I feel the frustration).
Aside from the derash, the plain meaning of the pasuk is hard to comphrehend. The generation who apparently didn’t get it, the generation that lived during the 40 years prior to Moshe’s words spoken here, was the dor de’ah, the dor that experienced yetzi’as Mitzrayim with all its miracles, the dor that stood at Har Sinai and personally witnessed kabalas haTorah. With all its faults, with all the trials in the midbar, this is the dor that Moshe thinks didn’t got the message? Isn’t the dor de’ah a generation that we hold up as exemplars of fidelity to Hashem?
The Sefas Emes explains that the previous generation lived in a cocoon, surrounded by Hashem’s presence, divorced from the world. Of course under those conditions they were close to Hashem. Moshe was telling the new dor that they alone had the challenge of trying to transform a lev so it has da’as, eynayim liros, oznayim lishmoa. It was this new dor that was charged with using the physical world in their avodas Hashem rather than sealing themselves off from it. That, the dor de'ah, for all its greatness, did not achieve.