William Walker Atkinson 
Clairvoyance and Occult Powers 

This book is a treasure chest full of occult wisdom. It includes twenty lessons on that will let the reader dive deep into his own powers, strange phenomena and spiritual wisdom. There is in every human being a sense which is not generally recognized as such, although nearly every person has had more or less experience regarding its workings. I refer to the sense of the presence of other living things, separate and apart from the operation of any of the five ordinary physical senses. I ask you to understand that I am not claiming that this is a higher sense than the other physical senses, or that it has come to man in a high state of evolution.