What is the main idea of El Etnografo by Jorge Luis Borges?

The main idea of El etnógrafo is about the secret to life or secret doctrine (as in the story) that cannot be written. Murdock, the ethnographer in the story, immerses himself into the indigenous culture and he learns to live as they do and think as they do. The tribes priests tells Murdock to document his dreams and to report them to him the next day and it is through his dreams that Murdock is enlightened to a certain truth in life. A truth that cannot be written or read, it is a truth/secret that can only be revealed through the simple yet extraordinary act of living.