Chapter 17 uses the metaphor of a swan separating milk from water. What is the significance of this analogy in understanding the choice between Shreya and Preya?

The analogy of the swan, or Maral, in Chapter 17 serves to illustrate the process of spiritual discrimination. The text explains that Shreya (the good) and Preya (the pleasant) are often blended in life, just as milk might be mixed with water. The swan, which is said to be able to drink only the pure milk, represents a courageous, intelligent, and wise individual. Such a person can discern the valuable path of Shreya from the allure of worldly Preya and chooses to cling only to Shreya. In contrast, the chapter notes that dull-witted individuals are incapable of this distinction and are conquered by Preya, embracing the diluted mixture.