LitCharts assigns a color and icon to each theme in The Hungry Tide, which you can use to track the themes throughout the work.
Language
Man vs. Nature
The Human Cost of Environmental Conservation
Idealism and Theory vs. Practicality and Action
Summary
Analysis
Kanai eats his lunch and then returns to Nirmal's study. He opens the notebook and begins to read. Nirmal explains that Kanai was one of the last people to see Kusum in 1970; she disappeared without a trace. As Nirmal's retirement approaches, he begins to think of how much life he wasted. He admits that he lied to Nilima—he's written nothing in the thirty years they've been in Lusibari and has also read very little. He's filled with regret and remorse.
The reader can hope that Kusum's disappearance without a trace means that she was safe from men like Dilip as well as the difficulties posed by life in the Sundarbans. Nirmal's regrets show that he's spent most of his life bogged down by theory and still feels unable to do anything about it.
Active
Themes
Other schools invite Nirmal to visit, and he accepts an invitation in Kumirmari. He misses his ferry for the long journey, but soon spots Horen and asks him to take him to Kumirmari. As they travel, Nirmal reads aloud from a book about the tide country by a Christian priest. The priest and his party first see a rainbow made by the moon. At this, Horen blurts that they must have been at Gerafitola, as he's seen the moon's rainbow there. Nirmal is dismissive and resumes reading. The party comes across Portuguese making salt, and again Horen adds where the priest must've been to see such a sight.
Horen's ability to pinpoint each location in the priest's story suggests that he's found a way to understand and learn about nature in a way that no other characters thus far have been able to. This situates Horen as someone who represents a middle ground in the fight between man and nature, given that he clearly knows his home very well and likely treats it with a great deal of respect.
Active
Themes
The next night, the party is treated to an amazing sight as glowworms light up the mangroves. They wonder if they're seeing "devils," and Horen is perplexed that they'd question it at all—he believes the sight is clearly the work of devils. Finally, the party is hit by a storm that came out of nowhere. Horen cries that they must have crossed "the line" into Dokkhin Rai's territory. Nirmal snaps that that's nonsense, and Horen suggests they agree to disagree. Nirmal addresses Kanai directly again to explain that he's sitting with young Fokir, while Horen and Kusum are out trying to discover if Morichjhãpi will actually be attacked.
While Nirmal means to engage with the book as a form of entertainment, it's clearly more than that for Horen—for him, it's simply more proof that the spirit world of the gods and the human world are connected, as local religion dictates is the case. Nirmal's unwillingness to go along with this is extremely disrespectful, and illustrates that simply sharing a language doesn't mean that Nirmal is fully willing to interact with Horen as an equal.