This quote comes from Chapter 23 of Jane Eyre, a novel by Charlotte Brontë. Jane says this in response to Rochester, who tells her to stop struggling "like a frantic bird." Jane responds that rather than being a bird, she has no net. She is free and can exercise her free will to leave Rochester, which she then chooses to do. The metaphor of a bird runs throughout this passage, as Rochester likens her to a bird, and Jane refuses to characterize herself as a creature who is locked in a cage. Rochester thinks of a bird as wild, while Jane sees a bird as caged. In this instance, Jane can exercise her free will, which makes her very different than Bertha, Rochester's wife who is locked away in the third floor of Thornfield, Rochester's house.