The teachers and prophets who had to give a message to humanity, who had to render a service to humanity, had such initiations even in their childhood. There is a symbolical story that the heart of the Prophet Mohammed was opened and some substance was taken out of it. People take this literally; but the real meaning is that a cover was torn away, and the soul was allowed to reach upward and go further on the path. There may be many such initiations, perhaps one or two or six or seven according to the state of evolution of the initiate.