In "My Sister's Keeper" by Jodi Picoult, the author reflects on the inherent openness of children's minds. Kids possess a natural curiosity and imagination that allows them to think freely and creatively. This perspective changes as one grows older; adulthood often entails conforming to societal norms and expectations, which can stifle that initial openness.
The quote suggests that maturity involves a gradual process of limiting one's thoughts and ideas. As individuals transition into adulthood, they tend to become more cautious and less adventurous in their thinking, akin to sewing up a previously open mind. This journey represents a loss of the uninhibited exploration that defines childhood, marking a shift toward a more structured way of understanding the world.