On the other hand, no other way of description is open. If there were mental states which are composed of other elements than sensations, they would necessarily remain indescribable; we could not grasp them because they would not have any definite relation to the common physical world. We might say, for instance, that our mental content is made up of sensations and feelings, but if such feelings were really entirely different from sensations, they would have to remain for all time mysterious and unknown. We could not compare notes. The feeling which I call joy may feel just like the one which you call despair. The consistent development of modern psychology and its emancipation from vagueness and superficial analysis became possible only through the fact that such recourse to indescribable elements has become unnecessary. Modern psychology has been able to demonstrate more and more that the same elements which constitute our perceptions are also the elements of the other contents of consciousness. In other words modern psychology has recognized that the volitions and emotions and feelings and judgments, and the whole stream of inner life, are made up of sensations. Millions of sensations in all degrees of vividness and clearness, of intensity and fusion, in endless manifoldness of rhythms and relations constitute their whole content. It is a discovery quite similar to the one which chemistry made when it found that the same elements which are part of the inorganic substances are also the only possible elements of the organic world.