The days after Passover and the day of Shavuot celebrate two events when the Jewish People received two important gifts, namely the grains of wheat and barley, harvested on the days between the two festivals and the Torah which we received on Mt. Sinai on Shavuot, the 50th day after Passover.
At this time of the year the Jewish farmer could really feel the truth of the saying "without flour there is no Torah and without Torah there is no wheat."
In Judaism the gift of Torah and the gift of wheat are connected; Torah gives physical existence spiritual content and makes the physically hard work involved to produce wheat to live worthwhile. Likewise physical life makes it possible to study Torah.
Building the temple where the two main activities were to study Torah and to make offerings of foodstuffs like animals, wheat, barley, fruit etc. was Judaism's way of reminding man of this moral lesson
In the year 70 CE the destruction of the temple resulted in the failure of the Jewish rebellion to regain their independence as a nation.
The strong desire of the Jewish People to renew national unity and national pride caused the Bar Kochba rebellion lead by Rabbi Akiva in the year 135 C.E. This rebellion also failed and brought greater devastation on the Jews than the catastrophe of the year 70 and further dashed the hopes of independence..
It's clear, from the time chosen to rebel, the 49 days of celebrating the wheat and barley harvest, that the Jews considered achieving national independence as important as harvesting the grains and receiving the Torah. The stated aim of the rebellion was to rebuild the temple. This is also evidenced by the minting of the famous Bar Kochba coins, showing the temple.
The Rabbis of blessed memory, instituted these days as days of mourning and the 33rd day after Passover, the day of cessation of a plague that broke out among the Jewish warriors, as a day of celebration.
It's clear that they considered that the Bar Kochba rebellion had brought the Jewish People to the brink of total annihilation.
In addition, as long as national aspirations remained alive the Jews couldn't settle down as loyal, productive citizens in a country where they had been dispersed. They would constantly fight to regain their lost homeland and the results would be similar to the results of the Bar Kochba rebellion
From now on they made it clear that the Jews would only continue to remember the lesson of mutual dependence between Torah and physical sustenance and not national revival, by replacing the functions of the temple but not the building of the temple..
They instituted the idea of the congregation (minyan) of 10 men gathering together at least 3 times per day to study the Torah and recite prayers, which are mostly Psalms, the words of the Prophets and other Biblical verses which Judaism considers the equivalent of sacrifices.
This is why the rabbis of blessed memory prevented the arousal of national sentiment by prohibiting customs demonstrating national pride such as the prohibition of blowing the ram's horn, excepting on the New Year, the prohibition of an orchestra in the synagogue and the kindling of the 7 branched candelabra.