Interpretation of verse 5-13
God is telling us that if one purifies the mind of evil thoughts, illness one has will become nonexistent. These dusts are greed, arrogance, self-love, regret, and covetousness. These are thought patterns, God tells us we must remove from our minds. God tells us by understanding the heart, we can do this.
Definitions:
Korekara: from now on
Ikana: whatever
Mutsukashi: difficult
Yamai: illness
Kokoro: mind
Shidai: depending
Naoran: incurable
Nashi: nonexistent