Billy discovers the need of light. In a big cave filled with scary enemies sometimes invisible you're lost as soon as the light disappears. He'll handle the dynamite carefully and wisely. The small tunnels connecting the different parts of the cave with each other can be helpful but also confusing. A long stay in the cave will certainly not destroy neither his will nor his courage - it might just make him LONG for next bunch of complications awaiting him at the end of the tunnel.