I think the reaon that the Author wrote this book so that he can show that no matter your situation therer is always hope and if you give up and don't do anything when you have a problem then you won't get anywhere. Everyday in this book eragon was trying to do something to stop King Glabtorix and if we doesn't contui this then therre is a great chance then The king will win. And thats Eragon NEVER gives up.

http://www.google.com/url?sa=i&rct=j&q=Eragon+vs.+King+Galbatorix&source=images&cd=&cad=rja&docid=PIwNI_lSFFXdqM&tbnid=NwvE-YNUv-LORM:&ved=0CAUQjRw&url=http%3A%2F%2Feverysinnerhasatagline.blogspot.com%2F2012%2F06%2Feragon.html&ei=iDV8Uv3uF5eu4APh0oGgDw&bvm=bv.55980276,d.dmg&psig=AFQjCNFn9oVi5suDlavNWj3mofowp_NydQ&ust=1383958279395372