On Yom Kippur the Jewish people received the second tablets, which were given quietly, not accompanied by thunder and lightning like the first ones. This may be explained with an analogy:

When a son is in his father’s household, his love for his father is not openly discernable, but rather hidden in the inner recesses of the soul and submerged in the joy of being in his father’s palace. On the other hand, when the son travels far away, then the love comes to the surface-the son pines for his father.

Yom Kippur is a day of pleasure, similar to the World to Come, a world of pleasure without eating and drinking. Moreover, it is also a day of joy, for in the World to Come there is no screen to separate Israel and their Father in Heaven. Then Israel will rejoice in their Maker, without any impediments or distractions.

When pleasure and joy are revealed, love is subsumed by them, remaining in the inner recesses of the heart. This is expressed in the giving of the second tablets without thunder and lightning, alluding to the “quiet” love within.

(Likkutei Torah Deuteronomy 41d)