And G-d came down on Mount Sinai (Exodus 19:20)
Once there was a king who decreed: "The people of Rome are forbidden to go
down to Syria, and the people of Syria are forbidden to go up to Rome."
Likewise, when G-d created the world, He decreed: "The heavens are
G-d's, and the earth is given to man" (Psalms 115:16). But when He
gave the Torah to Israel, He rescinded His original decree, and declared:
"The lower realms may ascend to the higher realms, and the higher realms
may descend to the lower realms. And I Myself will begin..."