To be able to understand this sentence, it's useful to consider a summary of "The Postmaster" by Rabindranath Tagore. This short story tells of a young man from Calcutta who arrives in the remote village of Ulapur to take up his duties as postmaster. He feels out of place and is unable to relate to the local people, most of whom work at an indigo factory. An orphaned village girl named Ratan cooks and does odd jobs for him. Out of boredom, the postmaster begins to teach her how to read. She, in turn, nurses him when he becomes ill. Because the postmaster and Ratan have no one else, they develop a relationship in which they are somewhat dependent upon each other.

When the postmaster decides to resign his post and move back to Calcutta, Ratan asks him to take her with him. When he refuses, he is unable to console her, and she runs off. As his boat gets underway, the postmaster has an impulse to go back and bring Ratan with him, but he does not act on it.

Now we return to the sentence in the question. The event the sentence refers to is the separation of the postmaster and Ratan when he leaves to return to Calcutta. Tagore writes that the postmaster consoles himself about leaving Ratan behind with "philosophical reflections." The word "unlettered" means "illiterate," and this is a fitting description of Ratan, who has had no formal schooling. Because Ratan has had no education, she is unable to fall back on the teachings of philosophy as consolation. Her heart is broken, and she has nothing at all with which to make herself feel better.