There is a main lesson in this book and that is to never give up or give in. I also know that this is the main lesson because when Percy Jackson takes up the weight o]f the sky he never gives up so it doesnt crush him. Thus when Percy Jackson loses his best friend Annabeth chase he never hive up to find her. He never gives in so the Drakon doesn't catch him and eat him. Percy Jackson never gives up or in so the authors message/lesson is to never give up. Anytime anywhere. I would rate this book a "10 out of 10" I wold recommend this book because it is very long and is a challenge even for advanced readers also. Additionally an unanswered question i would like to ask the author is how devastated was Percy Jackson when Luke Castellan betrays her? This book is legendary and is sure to make it feel like your in the book