How does the story of Somdev Buva illustrate the process of spiritual purification through a Guru's grace?

The story of Somdev Buva in Chapter 49 serves as a detailed case study in spiritual purification. Buva initially arrived with a critical and doubtful mind, but the process began with the overwhelming love he felt during darshan, which is described as a 'surge of love'. The key moment of purification, however, came through Baba's seemingly harsh actions. By confronting Buva with his own negative thoughts, Baba forced him into a moment of profound self-realization about his own ignorance versus Baba's wisdom and purity. Buva recognized Baba's 'anger' as a purifying instruction. The narrative concludes that by Sai's grace, the Swami 'became pure and stayed at His feet forever,' demonstrating that a Guru's grace can work in mysterious ways, including apparent anger, to dissolve a devotee's ego and 'bad desires' and establish them in a state of purity.