Sri Chinmoy: They only attack disciples who have already left my path. Or when the inner connection becomes loose, they can attack the disciple. If the connection is strong, how can they attack? Hostile forces compel you to surrender; then they mock at you. We are afraid of these beings because they are impure, and they are afraid of our purity.
One day a close friend of mine from the ashram was supposed to come to a play practice, but he did not come. For him not to come was extremely unusual. What happened was that he was attacked by a ghost. The ghost ruined his brain, and he became insane that very day. He became a street beggar, even though he was from a very rich family. He went to his friend's place and said, "Give me a bowl," and then he started begging. He walked hundreds of miles in a month's time. Then he came back to the ashram and stayed in the ashram for ten years. But when he came back he forgot all our names. He could not recognise us. It was not his bad karma but a hostile attack.