The Mastery of Love: A Practical Guide to the Art of Relationship (Toltec Wisdom Book) by Don Miguel Ruiz
Don Miguel Ruiz brings the Toltec philosophy to love and establishes the essential fact that one cannot love others until one fully loves oneself.
I first read this book when I was sixteen, and barely enduring the roughest adolescent years. I had no direction and was incredibly distraught, and this book brought me back. I could feel a complete turn-around then, and still do. It really shook me up, and I continue to read it from time to time. Miguel Ruiz's writing personifies clearly Toltec ideals, and never refrains to spread peace and love in me.