The Kotzker Rebbe defined the duality of giving and receiving as follows:
The festival of Shavuot is called the “Season of the Giving of our Torah” because on that day the Torah was given to Israel.
But as for the receiving of the Torah – each individual receives it according to his way, when he is ready to receive it.
The Giving of the Torah as an act of forming a connection between the Creator and His creatures is a one-time event – not only because it happened only once, but also because the disclosure that man is indeed capable of receiving things from the Infinite requires no further proof.
When the event is recalled, this suffices for it to remain meaningful.
Hence, there is a mitzvah to remember the day of the Giving of the Torah, to remember the event itself:
“But take heed and watch yourself carefully, so that you do not forget the things that your eyes saw… the day you stood before God your Lord at Horev.”
The memory of the event is its main content.
An analogy may be drawn from Norbert Wiener’s (regarded as the originator of cybernetics.) quip about the secret of the atom bomb:
The greatest secret about this bomb was revealed to the entire world on the day of the explosion – namely, that it is possible.
Similarly, the great secret and revelation in the Giving of the Torah lie in the very fact that the Holy One, blessed be He, is interested in giving the Torah, that He is interested in human beings and in the human individual to such an extent that it is His will to give him guidance regarding how he can attain closeness to Him.
For this reason, the Giving of the Torah is essentially a onetime act, unique in human history.
The event itself is the revelation of the content of the Giving of the Torah, and is sufficient in and of itself.
–Rabbi Adin Steinsaltz