from "Autobiography of a Yogi" by Paramahansa Yogananda

"As the power of a radio-broadcasting station is regulated by the amount of electrical current it can utilize, so the effectiveness of  a human radio depends on the degree of will power possessed by each person.

All thoughts vibrate eternally in the cosmos.  By deep concentration a master is able to detect the thoughts of any man, living or dead.  Thoughts are universally and not individually rooted; a truth cannot be created, but only perceived.  Any erroneous thought of man is a result of an imperfection, large or small, in his discernment.  The goal of yoga science is to calm the mind, that without distortion it may hear the infallible counsel of the Inner Voice."

-page 178