How does one cultivate a pure heart, and why is it essential for attaining spiritual knowledge?

According to the teachings in Chapter 17, a pure heart is cultivated through the performance of one's prescribed duties, known as Vihitakarma. This purity of heart is an indispensable prerequisite for attaining spiritual knowledge. The text states that action, or Karma, is the root cause of knowledge because the regular performance of one's duties cleanses the heart of impurities. Once the heart has been purified in this way, the crucial qualities of discrimination and detachment are born within it. This, combined with tranquility and self-restraint, places liberation within one's reach.