Described the outlook of the post man.

In Rabindranath Tagore's "The Postmaster," the postmaster proves to have a romantic, positive, and realistic outlook.
The postmaster proves to be a romantic given his reminiscing on life. (On a side note, Tagore's capitalization of the word "Nature" illustrates a Romantic perspective.)

On some evenings . . . the postmaster too would call up memories of his own home, of his mother and his sister, of those for whom in his exile his heart was sad,—memories which were always haunting him, but which he could not talk about with the men of the factory, though he found himself naturally recalling them aloud in the presence of the simple little girl.

Here, the postmaster's recollections on life illustrate his Romantic nature. His memories haunt him, and he wishes to share these memories with other men around him. Unfortunately, the men do not seem to possess the same Romantic nature. The postmaster is forced to share these memories with only the little girl. The postmaster also "tried his hand at writing a verse or two." This attempt at poetry writing illustrates his Romantic nature as well.
The postmaster also possesses a positive outlook. Although he does not wish to move to Ulapur from Calcutta, he does so. Although not openly spoken of, the postmaster seems to be the type of person who faces challenges with a positive outlook. The pay is less, the town smaller, and he feels like a "fish out of water." That said, he accepts the position. One could infer that the postmaster simply accepts the path in his life and chooses to face it with positivity.
The postmaster is also realistic. He realizes that the men at the factory will not understand his romantic notions. He also realizes that the young girl, Ratan, is the only company he will have. With this understanding, the postmaster is realistic in the relationship he creates with the young girl. He takes on the role of a father, even being called "Dada."
His realistic outlook continues as he realizes that he can no longer live the life he is living. He quits his job as the postmaster, and he decides to return to Calcutta. Ratan asks to go with him, but he refuses to take her. He is realistic about their relationship, and he understands that it cannot continue past his position as the postmaster.
Overall, the postmaster proves to be a very simplistic man. He takes what he has been given and does the best he can. Once he realizes that he can no longer proceed down this path, he accepts another path in life.