As Margaret visits Helstone for the first time since her parents' deaths, the novel uses light imagery and also personifies nature to contrast Helstone with her personal situation.
Every mile was redolent of associations, which she would not have missed for the world, but each of which made her cry upon ‘the days that are no more,’ with ineffable longing. [...] Now she was alone, an orphan, and they, strangely, had gone away from her, and vanished from the face of the earth. It hurt her to see the Helstone road so flooded in the sunlight, and every turn and every familiar tree so precisely the same in its summer glory as it had been in former years. Nature felt no change, and was ever young.
The word "redolent" has to do with the sense of smell. In this case, the word is probably used in a metaphorical sense, but the point is that as Margaret travels closer to Helstone, familiar associations provoke nostalgia as overwhelmingly as a strong scent might do.
Further, the approach to Helstone is "flooded with light," and marked by "summer glory," lively, radiant visual imagery that jars with Margaret's painful feelings of grief. The contrast is so painful because it appears that Helstone hasn't changed at all since the Hales lived there, whereas Margaret has endured terrible losses in the meantime. When nature is personified as "[feeling] no change" and never aging, the reader is meant to sympathize with Margaret's sadness in recognizing that she has changed and that both her parents have died. This contrast anticipates Margaret's ambivalent homecoming.
