In this book "Jonathan Livingston Seagull" the author has emphasized two things, one of which is that you don't have to live within your limits even if everyone is doing it because it is your life and you've got the freedom to live it how you want while the second thing is that your body is not your limit but it is just a thought you think.
The Author being deep in his spiritual knowledge has described in his way the importance of Spirituality in one's life as well as the Boldness to separate from those who don't understand the joy of doing things that we like, in this case, the seagull had the joy of flying while others seagulls were flying just for the sake of finding food.
Other than this, the Author showed the Compassion of Jonathan towards his flock that they too should learn to be free and transcend the limits to live freely and enjoy what is given to them.