What analogy does Chapter 17 use to illustrate the relationship between Shreya and Preya, and what does it teach about making the right choice?

In Chapter 17, the relationship between Shreya (the Good) and Preya (the Pleasant) is illustrated using the analogy of milk mixed with water. Just as these two substances are blended together, the paths of salvation and worldly joy are intertwined in life. The chapter teaches that a courageous and wise person should act like a swan (Maral), which is fabled to be able to separate milk from water, drinking only the pure milk. This metaphor emphasizes that the true purpose of human life is to develop the discrimination necessary to choose Shreya and turn away from Preya, even when they are presented together.