How does the source describe Sai Baba's understanding of the Gita, and why was this considered remarkable?

Chapter 39 highlights the remarkable nature of Sai Baba's spiritual knowledge, particularly concerning the Gita. The narrator expresses wonder about how Baba, who had no formal training in Sanskrit and was not known to have ever studied the Gita, could grasp the very heart of its meaning. This is presented as a testament to the fact that the knowledge of Saints is often beyond conventional understanding and reach. Despite his apparent lack of scholarly study, Sai Baba demonstrated a profound insight into the Gita's essence simply by posing a deep question about the verse Nana was humming, showing he was a true "knower of the heart of the Gita's meaning."