For the second time, Isaiah asks, "Do you not know? Have you not heard? He asks this for emphasis. This is a key principle about God, but it is also one we have difficulty grasping. God doesn't get tired. He doesn't need to rest or sleep. He has everything under control. And his understanding is inscrutable. The Hebrew means his understanding is outside of our ability to discover or search or measure. Imagine how God's limitless understanding impacts your relationships and your work.