"When you want to become a master or a guru, what do you have to master? Your own senses. That's called 'master.' Master of you. Mastership is control over your own lust, anger, greed, hatred, jealousy, envy, fear. These are the seven basic enemies. Only when you can conquer these basic enemies are you a master, a guru. And only God will give you the command, to be a true teacher."
"A man of realization does not perform any miracles until he receives an inward sanction. God does not wish the secrets of His creation revealed promiscuously*. Also every individual in the world has an inalienable right to his free will. A saint will not encroach on that independence."
-Swami Sri Yukteswar Giri
*(In Autobiography of a Yogi, Parmahansa Yogananda includes this footnote: "Give not that which is holy unto the dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you." - Matthew 7:6)