When the sea split, the angels fell behind. Rabbi Levi Yitzchak of Berditchev reads the verse, "The angel of God who had been traveling in front of the Israelite camp moved to their back" (Exodus 14:19), as evidence that at the moment of the splitting, the Jewish people ascended to a spiritual level higher than the highest-ranking angels.
Angels are inherently holier than human beings. They are pure spirit, uncorrupted by physicality. But whenever God displays His love for Israel, the hierarchy inverts. At the shores of the sea, the Israelites were elevated so dramatically that the angel who had been leading them could no longer stay ahead. He moved behind, because they had surpassed him.
The Midrash (Sh'mot Rabbah 21:6) records that when Moses commanded the sea to split in God's name, the sea refused. "Son of Amram," it said, "I am greater than you. I was created on the third day. Man was not created until the sixth." The sea had been faithfully performing its task for thousands of years and had forgotten that it was not an independent force but an instrument of the Creator's will.
Rabbi Levi Yitzchak sees this as a universal pattern. Nature, given enough time, begins to imagine itself sovereign. The splitting of the sea was God reminding nature who is actually in charge. Had the sea obeyed immediately, the humbling would have been minimal. Because it resisted, it had to be turned into dry land, a far more dramatic demonstration of divine sovereignty.
This is also the meaning of Moses' opening line in the Song of the Sea: "For He is highly exalted" (Exodus 15:1). The Hebrew ki ga'oh ga'ah echoes the sea's own arrogance (ge'ut), turned back upon itself. The sea that considered itself mighty was overwhelmed by the One who is truly exalted. And the people who walked through on dry ground sang because they had just experienced, for one blazing moment, what it feels like to stand above the angels.