"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)