What is the theme in Christ Stopped at Eboli by Carlo Levi?

A constant theme of Christ Stopped at Eboli is poverty, both spiritual and economic. The people of Gagliano are not merely poor, they are shockingly poor. The land does not effectively grow food. The forests for the most part have been harvested. The rivers have been drained and redirected such that they are shrunk to streams that often dry up. Livestock and other animals are rarely seen. For some reason, the State tries to force the South to grow wheat, which is not compatible with the soil. The people try to raise livestock, goats in particular, but the State gets in their way; for instance, they tax goats to the degree that they aren't worth keeping alive.