Swami Panchadasi 
Clairvoyance and Occult Powers [EPUB ebook] 

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…