Our hidden forces La psychologie inconnue An experimental study of the psychic sciences. This book, "Our hidden forces La psychologie inconnue An experimental study of the psychic sciences. Volume 25", by Émile Boirac, is a replication of a book originally published before 1917. It has been restored by human beings, page by page, so that you may enjoy it in a form as close to the original as possible. This book was created using print-on-demand technology. Thank you for supporting classic literature.