Why does the author describe the postmaster as a fish out of water?

The postmaster feels like he doesn't belong in the small village of Ulapur. He contrasts this remote rural backwater with the thrusting metropolis of Calcutta, which is where he'd much rather be. The postmaster is a very well-read, intelligent man who grieves over the ignorance and lack of sophistication of the villagers. With snobbish disdain, he looks down on them as unworthy companions for decent, upstanding folk such as himself.
Not only is Calcutta more civilized in the postmaster's eyes, it's also a good deal more hygienic than Ulapur. In the village, the people bathe in the local river, a custom that the postmaster finds abhorrent. He, on the other hand, chooses to bathe in water drawn and kept in pitchers in the time-honored Calcutta fashion.