Amos, unlike most other prophets of his day, was not employed by the state. His main theme was justice. Yahweh was just, he maintained, and any people who considered him to be their God must also be just.
Amos is depicted as an old man, leaning wearily on one arm, holding a scroll in his hand. Perhaps it is an early draft of the oracles he delivered to the Israelites at Bethel.
A judge is delivering a verdict to a poor family -- note the bare feet of the wife and husband as contrasted with the sandals and elaborate robe of the judge.
Scales of Justice
The invisible hand of God unashamedly tips scales of justice in favour of the poor family in the pane above.