When we look at the life of the prophet Amos in the first reading, we can understand this. Amos was just a shepherd and a dresser of sycamore-fig trees. If Amos were to be a prophet, what basis would there be? The cost Amos brought to his preaching was a life of poverty. A life of poverty is more convincing because, in a sense, a poor person is freer and not subject to any king. If you take someone else's possessions, can you still criticize them?