Philosophy, which is the fourth stage of development, has five aspects: physical, intellectual, mental, moral, and spiritual. These cannot be learned by the mere perusal of books, and by listening to the discussions of philosophers. For philosophy is not a study which is taught in the universities alone; it contains quite an opposite path to knowledge, and it can only be truly studied under the guidance of a murshid. In him the mureed has perfect trust and confidence, as complete discipline even to the sacrifice of free will is required. At first this appears to be a loss of individuality, while the ego rebels at being thus crushed and submerged beneath the stronger laws of will and reason. But the battle against self gives a mastery over self in the end, which in other words is a mastery over the whole universe.