缩句：
In the book "Christmas in Camelot," the main character, Jack, learns a valuable lesson about the importance of kindness and helping others. He learns this lesson through his interactions with King Arthur and his knights.
One piece of text evidence that shows how Jack learns this lesson is when King Arthur asks him to help prepare the Christmas feast. Jack agrees to help but feels overwhelmed and unsure of his abilities. However, as he starts chopping vegetables and doing other tasks, he realizes that with some effort and determination, he can be helpful and make a difference. This shows Jack that even though he may doubt himself at first, he is capable of doing important things.
Another text evidence that demonstrates Jack's lesson is when he discovers a secret, hidden room where King Arthur keeps all the gifts he plans to give to the villagers. Jack learns that King Arthur spends the whole year collecting and preparing gifts for the villagers because he wants to make them happy. This teaches Jack the importance of generosity and thinking of others' happiness, which helps him understand the true meaning of Christmas.
Overall, Jack learns his lesson through his experiences of helping with the feast and discovering the secret room of gifts. These experiences show him that even small acts of kindness can have a big impact and that thinking of others brings joy and happiness.