The Yaksha asked,—‘With what is the world enveloped? What is that owing to which a thing cannot discover itself? For what are friends forsaken? And for what doth one fail to go to heaven?’ Yudhishthira answered,—‘The world is enveloped with darkness. Darkness doth not permit a thing to show itself. It is from avarice that friends are forsaken. And it is connection with the world for which one faileth to go to heaven.’

In plain words: Yudhishthira says the world is covered by darkness (ignorance), and darkness keeps things from being seen. Greed makes people abandon their friends, and being too attached to worldly things keeps people from reaching heaven.