Thorn: Book 2 in The Grove Trilogy

It has always been a conversation among the animals, why the willows decided that man would be born without fur, fang, or claw. Even the plants can defend themselves in their own ways, with poison or concealment, with tough bark or piercing thorn. Why would the willows send out man naked and defenseless? But there is a very old story which few care to remember anymore: the willows, loving man so, hid a Thorn deep inside of him so that he might bring it forth in times of great need. If this is true, then how can one steal a Thorn? And if this young man has lost his Thorn, who can reclaim it?