According to the source, what are the primary obstacles that conceal knowledge, and how are they illustrated?

In the wisdom shared in Chapter 50, lust and anger are identified as primary obstacles that prevent knowledge from shining forth. The text uses powerful imagery to illustrate how these forces work. It explains that just as 'a clean mirror is covered by dust' or 'the light of fire is obscured by smoke,' the inherent light of knowledge is similarly 'hidden by ignorance' when a person is overcome by lust and anger. This demonstrates that the path to knowledge requires a purification of the mind from these powerful emotional disturbances, a process for which devotion is prescribed as the remedy.