The finite centre of experience, therefore, is real, even though its reality is too profound to be intellectualized. What then is the characteristic feature of the ego? The ego reveals itself as a unity of what we call mental states. Mental states do not exist in mutual isolation. They mean and involve one another. They exist as phases of a complex whole, called mind. The organic unity, however, of these interrelated states or, let us say, events is a special kind of unity. It fundamentally differs from the unity of a material thing; for the parts of a material thing can exist in mutual isolation. Mental unity is absolutely unique. We cannot say that one of my beliefs is situated on the right or left of my other belief.