The criterion of reality is self-consistency. We cannot think that anything is ultimately real which has its ground of existence in something else. A real thing is that which can be explained without reference to some other thing. Reality, therefore, is completely self-contained existence, not merely dependent existence. Contradictions cannot be true. If we have to affirm a contradiction of anything, it must be due to an {39} appearance, and the reality must reconcile the contradiction. The idea of reality, therefore, is the idea of perfect harmony. Knowing, then, what reality is, can we say that there is any actual object of thought that conforms to it? And have we in our limited experience anything that will guide us to the attainment of this object? The idealist is confident that we have. Some things seem to us to possess a far higher degree of reality than others, just because they conform in a greater degree to this ideal of harmonious existence. It is when we compare the reality of physical things with the reality of mental things that the contrast is most striking, and in it we have the clue to the nature of the higher reality. Physical reality may seem, and indeed in a certain sense is, the basis of existence, but when we try to think out the meaning of physical reality, it becomes increasingly abstract, and we seem unable to set any actual limit to prevent it dissipating into nothing. In physical science we never have before us an actual element, either matter or energy, in which we can recognise, however far below the limit of perceivability, the ultimate stuff of which the universe is composed. Science has simply to arrest the dissipation by boldly assuming a matter that is the substance and foundation of reality and an energy that is the ultimate cause of the evolution of the universe. On the other hand, when we consider mental existence, the pursuit of reality is in an exactly contrary direction. There, the more concrete, the more comprehensive, the more individual a thing is, the greater degree of reality it seems to have. In the spiritual realm, by which we mean, not some supposed supra-mundane sphere, but the world of values, the world in which ideas have reality, in which we live our rational life, reality is always sought in a {40} higher and higher individuality. The principle of individuality is that the whole is more real than the parts. An individual human being, for example, is a whole, an indivisible organic unity, not merely an aggregation of physiological organs with special functions, nor are these a mere collection of special cells, nor these a mere concourse of chemical elements. The State as a community is an individual organic unity with a reality that is more than the mere total of the reality of individual citizens who compose it. It is this principle of individuality that is the true criterion of reality. It is this principle that, while it