Jews were commanded that, upon crossing the Jordan and entering Eretz Yisrael, they were to take large stones, cover them with plaster and write upon them all of the Torah in 70 languages (Devarim 27:2-3). Which came first -- the plaster or the writing?

Rabbi Shimon says that they first covered the stones with plaster and then wrote upon the plaster. Rabbi Yehuda, however, points out that a few passages later (Ibid. 27:8) the Torah explicitly commanded to write upon the stones. He therefore concludes that the writing was upon the stones themselves and these stones were then covered with plaster.

According to your approach, Rabbi Shimon challenged Rabbi Yehuda, how was it possible for the nations of the world at that time to learn the Torah? (How did the ancient nations study the Torah, which was written in 70 languages to make it available for anyone who wished to study it in order that no one should have an excuse that he had no opportunity to learn the Torah? -- Rashi)

Hashem instilled a special flash of wisdom in those nations, explained Rabbi Yehuda, and they sent their scribes to scrape off the plaster, copy the Torah and bring back to them its contents. Their failure to take advantage of this opportunity to learn and live by that Torah, he concludes, sealed the fate of their spiritual status.

The obvious question that arises in regard to Rabbi Yehuda's response to Rabbi Shimon's challenge is: Why was it necessary for the words of the Torah to first be concealed with plaster and then revealed through the efforts of the scribes?

It may be that this was intended as a lesson that one can only truly acquire Torah knowledge if he is ready to invest serious effort in studying and understanding the words of the Torah. There are people who may have a curiosity about Torah but want its contents handed to them on a silver platter, like the person who came before the Sages Hillel and Shammai requesting that they convert him to Judaism on the condition that they teach him the entire Torah while he stands on one leg (Mesechta Shabbat 31a). To dispel any notion that Torah can be acquired without hard work, our ancestors were commanded to cover the multilingual recording of the Torah with plaster so that the nations who really wished to learn would first have to sweat a little along with their study.

Sotah 35b

When the kohanim pronounce their blessing upon the congregation, those who stand behind them are not included as the beneficiaries of their blessing. If, however, there are Jews who are unable to be present in the synagogue during the kohanim's blessing (which were then part of the daily service, and continue so even today in many communities in Eretz Yisrael) because they are at work in the fields, they too are included in the benefit of the blessings.

When the question was raised as to whether people who do come to the synagogue but are separated from the area of the kohanim by a barrier are included in the blessing, this dramatic ruling of Rabbi Yehoshua ben Levi was cited:

"Even an iron curtain cannot stand between Jews and their Heavenly Father."

Tosefot explains why those Jews behind the barrier are included in the blessing of the kohanim, even though nothing prevents them from being present in the area of the kohanim with nothing between them, while the ones who stand behind the kohanim are not included. The latter, he points out, demonstrate that they attach no significance to the kohanim's blessing which the Torah ordered to be given face to face. This is not the case in regard to those who stand behind the barrier, and the blessing reaches them because "iron curtains" cannot stand in the way of Hashem's blessing reaching them through the kohanim.

Tosefot also points out that the "iron curtain" concept also applies to communal prayer. Even though a barrier can interfere with the ability to combine separate groups of individuals into the minyan (quorum of ten) needed for communal services, it does not prevent an individual behind a barrier separating him from a minyan from answering amen, barchu and kedusha and even fulfilling his obligation of prayer through listening to the shliach tzibur (cantor). (See Shulchan Aruch Orach Chaim 54:20 for more details on this issue.)

What about the "iron curtain" which Rabbi Elazar (Mesechta Berachot 32) says has stood between us and our Heavenly Father since the destruction of the Beit Hamikdash? Tosefot makes the distinction that this statement was a comment on the difference between how acceptable our prayers were during the time of the Beit Hamikdash and after its destruction. That barrier does exist but no iron curtain exists before Hashem when it comes to the question of kohanim blessings and communal prayers penetrating them.

Sotah 38b