6:16 and they said to the mountains and to the rocks, "Fall on us and hide us from the presence of Him who sits on the throne, and from the wrath of the Lamb;

and they said to the mountains and to the rocks, "Fall on us and HIDE us

This request is also predicted in the Old Testament in Isaiah 2:19-22.

Sin always causes man to want to HIDE from GOD. Just trying to hide from GOD causes distress as Israel found out in Hosea 10:8-10. It is clear that as Christ was on the way to Calvary and His earthly death, this retribution was on His mind. He quotes from this same Hosea passage of scripture, Luke 23:28-31. He was/is fully aware of what Calvary means and its place among the seven seals of Revelation.

The wrath of the Lamb appears to be a contradiction. How can a lamb, meek and docile, display wrath? (John 5:26-27). From here on, the "Wrath of the Lamb" is a recurring theme. Look for it!