That we have a direct consciousness of freedom is the doctrine of most of the writers on moral science. Cousin is emphatic in the assertion of this doctrine: "I am conscious of this sovereign power of the will. I feel in myself, before its determination, the force that can determine itself in such a manner or in such another. At the same time that I will this or that I am equally conscious of the power to will the opposite; I am conscious of being master of my resolution, of the ability to arrest it, continue it, repress it."[523] The distinguished Professor of Moral Philosophy in the University of Edinburgh, Dr. Calderwood, teaches the same doctrine: "It is in our consciousness of self-control for the determination of activity that we obtain our only knowledge of causation. Every one knows himself as the cause of his own actions. In the external world we continue ignorant of causes, and are able only to trace uniform sequence, as Hume and Comte have insisted. But in consciousness we distinguish between sequence and causality. We are conscious of our own causal energy by knowing the origin of our activity in self-determination."[524] The direct consciousness of freedom is denied by Sir William Hamilton. This denial is a necessary consequence of his doctrine of relativity. If we are not conscious of self as a reality, but only of certain modes or affections, then, of course, we can not be conscious of self as a free power. But as Mansel has forcibly replied: "Does it not rather appear a flat contradiction to maintain that I am not immediately conscious of myself, but only of my sensations or volitions? Who, then, is the _I_ that is conscious; and how can _I_ be conscious of such states as _mine_? In this case it would surely be more accurate to say, not that I am conscious of my sensations, but that the sensation is conscious of itself; but, thus worded, the glaring absurdity of the theory would carry with it its own refutation.... Self-personality is revealed to us with all the clearness of an original intuition."[525] With an inconsistency which shows the fallacy of Sir William Hamilton's whole theory of relativity, he admits that, "As clearly as I am conscious of existing, so clearly am I conscious at every moment of my existence that the conscious Ego is not itself a mere modification, nor a series of modifications of any other subject, but that it is itself something different from all its own modifications, and a _self-subsistent entity_."[526] If, then, we admit, as we must admit, the existence of an immediate consciousness, not merely of the phenomena of mind, but of the personal self as actively and passively related to them, we must also admit the direct testimony of conscience to the fact of liberty. "I am conscious not merely of the phenomenon of volition, _but of myself as producing it, and as producing it by choice, with a power to choose the opposite alternative_."