Regarding your request for a free PDF version of the book, I couldn't find any direct links to download "Una mente en paz consigo misma" by Byron Katie for free. However, I can suggest some alternatives:

: Puedes comprar el libro en formato electrónico en tiendas en línea como Amazon, Google Books, o Apple Books. Algunas de estas plataformas ofrecen previews gratuitas.

In this book, Byron Katie uses the Diamond Sutra as a framework to explain how a mind that has questioned its stressful thoughts becomes "at home with itself". The guide to this peace involves: The Work Resources - The Work of Byron Katie