The quote "You are only a prisoner when you surrender" suggests that one's mindset determines their freedom. It implies that as long as an individual maintains their will and resilience, they can avoid becoming a captive, whether physically or mentally. This view highlights the significance of personal strength and determination in overcoming challenges and adversities in life.

In the context of Tad Williams' book "Shadowplay," this concept is essential for the characters' development. It stresses the importance of fighting against internal and external demons and emphasizes that true imprisonment comes from giving up rather than being confined by circumstances.