After one has practiced these three aspects of discipline, one is able to arrive at the fourth aspect which is greater; it is greater, because in this way one arrives at spiritual experience. That discipline intends to free one's consciousness from one's environment. This is the experience of the adepts who have worked at it for a long time in order to achieve it. In the old schools of the Sufis, and even to-day, there is the custom that, when they arrive in the room of meditation, or when they go out of it, one of them is there to suggest this idea in words. He says, "Solitude in the crowd", which means: when you are in the midst of the crowd, even then you can hold your tranquillity, your peace; you are not disturbed by the environments. It is this which enables one to live in the midst of the world and yet progress spiritually. It takes away that necessity which compelled many souls in ancient times to go to the wilderness in order to develop spiritually.