Amos Sees the Plumbline Beside a Crooked Wallby emmanuel_higgins

Amos 7:7

Thus he shewed me: and, behold, the Lord stood upon a wall made by a plumbline, with a plumbline in his hand.

The plumbline in the Lord's hand is the standard by which He measures and tests both nations and individuals. In that measuring He assigns to each its appointed place in His plan. His judgment by that standard is without error. The test shows that each nation and each person is deciding its own destiny by its own choice. Even so, God overrules the course of events to accomplish His purposes.