Q: What did Klal Yisroel do in the midbar to prepare for Matan Torah?
A: What did they do to prepare for Matan Torah? So we know Hakadosh Baruch Hu told Moshe Rabbeinu beforehand what to say to the people.
So shall you say to the House of Yaakov and tell the sons of Yisroel (Shemos 19:3).
What did He say? “You, the whole nation, will be for Me a special treasure from all the nations” (Shemos 19:5). “I’m going to do something now,” said Hashem, “that’s going to change the nature of the entire people. The whole Klal Yisroel will become different now. If you will stand at Har Sinai and you say, ‘Na’aseh v’nishma; yes, Hashem, we accept You forever and ever,’ then I’m going to make you into an Am Segulah, an exceptional type of people.”
Now, Am Segulah doesn’t merely mean “I’m going to give you semichah; I’m going to give you a rabbinical certificate to hang on the wall and you’ll be honored just by the title.” No; it’s much more than that.
Segulah means that your nature is going to change. Your character will be entirely metamorphosed and you’ll become an entirely different type of people. At Har Sinai not only did we adopt certain attitudes and promise to remain faithful to them, but we became an entirely different people than we were before.
That’s what Hashem said then: “And you will be for Me a Kingdom of Kohanim and a Holy Nation” (ibid. 6). “Take these words and tell it to the Bnei Yisroel” (Shemos 19:6). “Make sure the people understand what I’m saying now very well,” Hashem said to Moshe Rabbeinu. Because it wasn’t just a promise of reward for accepting the Torah – it was being proposed as part of the acceptance, part of Kabolas HaTorah.
And you can be sure that Moshe Rabbeinu was masbir to them, he explained to them what it means to be a kingdom of priests. That’s how they prepared. Moshe told them Mamleches Kohanim means we’re all kohanim to serve Hashem. That’s your job in this lifetime. Your entire history should be like a kohen, someone who’s devoted to serving Hashem.
Now, I wasn’t present. I could only guess some things, but that’s the idea that he spoke to them, about the greatness of choosing to accept the Torah and the function in the world as a nation to serve Hashem.
And when you accept the Torah, you’ll be a holy nation. Moshe spoke at length; he gave them a peirush on that. How accepting the Torah means becoming a holy nation, a nation that strives for perfection.
So there’s no question that the Bnei Yisroel were thinking about these great ideals, these great requirements that were included in accepting the Torah. They prepared by means of thinking.