In the quote from Susan Cooper's "Silver on the Tree," the author emphasizes the importance of free will in the lives of individuals. She expresses her belief that no external force can dominate a person's mind, asserting that the ability to choose is inherently granted by God. This perspective highlights the significance of individual agency and personal responsibility.

Cooper suggests that the only constraints on our decisions arise from the influences of other people, not from any divine or cosmic power. This idea underscores the value of personal choice and reinforces the notion that our actions and paths in life are ultimately shaped by our own decisions, free from coercion or predestination.