This isolation is reflected in the great development of that branch of philosophy known as epistemology--the theory of knowledge. The identification of mind with the self, and the setting up of the self as something independent and self-sufficient, created such a gulf between the knowing mind and the world that it became a question how knowledge was possible at all. Given a subject--the knower--and an object--the thing to be known--wholly separate from one another, it is necessary to frame a theory to explain how they get into connection with each other so that valid knowledge may result. This problem, with the allied one of the possibility of the world acting upon the mind and the mind acting upon the world, became almost the exclusive preoccupation of philosophic thought. The theories that we cannot know the world as it really is but only the impressions made upon the mind, or that there is no world beyond the individual mind, or that knowledge is only a certain association of the mind's own states, were products of this preoccupation. We are not directly concerned with their truth; but the fact that such desperate solutions were widely accepted is evidence of the extent to which mind had been set over the world of realities. The increasing use of the term "consciousness" as an equivalent for mind, in the supposition that there is an inner world of conscious states and processes, independent of any relationship to nature and society, an inner world more truly and immediately known than anything else, is evidence of the same fact. In short, practical individualism, or struggle for greater freedom of thought in action, was translated into philosophic subjectivism. 2. Individual Mind as the Agent of Reorganization. It should be obvious that this philosophic movement misconceived the significance of the practical movement. Instead of being its transcript, it was a perversion. Men were not actually engaged in the absurdity of striving to be free from connection with nature and one another. They were striving for greater freedom in nature and society. They wanted greater power to initiate changes in the world of things and fellow beings; greater scope of movement and consequently greater freedom in observations and ideas implied in movement. They wanted not isolation from the world, but a more intimate connection with it. They wanted to form their beliefs about it at first hand, instead of through tradition. They wanted closer union with their fellows so that they might influence one another more effectively and might combine their respective actions for mutual aims.