Yahweh said to me, "Amos, what do you see?" I said, "A plumb line." Then the Lord said, "Behold, I will set a plumb line in the midst of my people Israel. I will not again pass by them any more.
They've become so crooked. God laid the plumbline in order that, of course, the purpose of the plumbline is to make the straight corner, the straight wall. God held the plumbline and He could see the crookedness, the perversity.