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He also discusses tapah (austerity) and describes the austerities of the speech, body, and mind. Shree Krishna then moves to the subject of yajña (sacrifice) and explains that based on the modes of nature, sacrifice can manifest into varied forms. He also classifies food into three categories and discusses the impact of each category upon humans.
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The quality of life they lead is determined by the nature of their faith, including the food they prefer to eat. However, depending upon the nature of their mind, their faith adapts a corresponding color: sāttvic, rājasic, or tamasic.
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In the beginning, He discusses faith as an inseparable aspect of human nature and says that everyone holds faith. In this chapter, He goes deeper into the subject. Earlier in chapter fourteen, Shree Krishna had explained the three gunas or modes of material nature and how they govern human behavior.
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