If you were specifically looking for a talk titled "El poder de las palabras," you can watch his full lectures on YouTube for free. This is often better than a PDF summary.
If you are interested in Sigman's research on words, consciousness, and the brain, this is the book you should read.
If you do not want to purchase the physical book from a bookstore (like Amazon or local retailers), here are the best ways to access the ideas for free or at a low cost: libro el poder de las palabras mariano sigman pdf gratis top
A. The "El Poder de las Palabras" Conferences (Video) This book was born from a conference cycle. Much of the core content Mariano Sigman discusses is available visually for free on YouTube.
B. Public Libraries
C. Audiobooks
D. Official Articles and Essays
Be very cautious of websites promising a direct PDF download of this book.