Why is having a Guru considered so essential for overcoming ignorance?

Chapter 50 strongly emphasizes the indispensable role of a Guru in dispelling ignorance. The text explains that ignorance often manifests from doubt (vikalpa), which can corrupt even a wise person's knowledge and lead to pride. It gives the powerful example of Shuka, a supreme knower who still suffered loss because of doubt. The text explicitly states that ignorance arising from doubt "cannot be removed without a Guru." It uses the analogy of a drop of fermented gruel spoiling a whole pot of milk to illustrate how doubt contaminates knowledge. Therefore, a Guru is necessary to help purify the mind and remove these deep-seated doubts, allowing for the manifestation of true, infinite knowledge and the attainment of non-dual Samadhi.