It is impossible to understand the beginning of our parasha without connecting it to the end of Parashat Devarim. There we find Moshe giving instructions to the tribes that decided to stay in the East Bank of the Jordan: “I commanded you at that time: ‘Hashem gave you this land to inherit it; you shall go forth as a vanguard before your brothers, Bnei Yisrael, all men of army age” (Devarim 3:18). It was actually Moshe’s words of criticism to these tribes that gave him the resolve to beg and pray before Hashem to let him enter the Land beyond the Jordan.
In our parashah, Moshe returns the second generation since the Exodus to the account of the greatest event in the history of mankind – the revelation and giving of the Torah on Sinai. This was the foundation of the status of Am Yisrael as Hashem’s nation, the only nation to whom Hashem revealed Himself. For that reason, Chazal saw the 600,000 plus who stood at the bottom of the mountain as the representatives of all future generations of Bnei Yisrael, as even those who were present only spiritually were included in the covenant. The closeness that was forged at Sinai turned all members into a nation of “prophets and sons of prophets.”