Transformation has many facets in Nectar in a Sieve. Characters are transformed by hardship, learning how to endure and transcend difficulties. The town is transformed by the tannery, which disrupts caste traditions and the environment. The world is becoming modern and industrial, a change from rural and agricultural. Characters’ values change when faced with the reality of what poverty drives people to do (prostitution, thievery, etc), and their own hopes for themselves are gently dimmed and often redirected throughout the novel. Change is inevitable, and the story directs its focus toward watching people grow and adapt to the world as it changes around them. They have no choice but to transform if they are to survive, and this transformation occurs socially, but also personally.
It’s not India’s political situation alone that changes in the book, it’s the Indians themselves. Note that all Nathan and Ruku’s children do exactly the opposite of what’s expected of them, and their parents are powerless to do anything about it. The book is about changes that were occurring with the new generation of Indians, as India was going through its own national growing pains.
Rukmani has changed over the course of the story; the woman she describes at the start of the novel is young and flush with hope. The reason the book is so focused on suffering and failure is because Ruku, retrospectively, realized those things were the greatest influences in her life, and they’ve changed her into a resigned (but content) old woman.