Craving and Ignorance

Ajita asked: "What is it that smothers the world and makes it so hard to see? What is it that pollutes the world and seems to threaten it?" The Buddha answered: "It is ignorance that smothers, and it is carelessness and greed that make it invisible. The hunger of craving pollutes the world, and the pain of suffering causes the greatest fear."

- Sutta Nipata